C# SqlBulkCopy failing to initialize on connection error but only in a certain package

Question

I am running the following code to bulk insert an Excel sheet into SQL Server. It works fine in a standalone package, but the moment I place it into my primary ETL package, it fails with a connection error.

The code fails here every time as soon as I attempt the SqlBulkCopy saying

Value cannot be null - Parameter: connection

It runs flawlessly in a standalone package so I'm wondering what might I have done in my other package to cause a config error or something else?

// Use the ADO.NET connection and Load the data from DataTable to SQL Table
SqlConnection myADONETConnection = new SqlConnection();
myADONETConnection = (SqlConnection)(Dts.Connections["DMDSQL"].AcquireConnection(Dts.Transaction) as SqlConnection);

MessageBox.Show("SQL Connection is open");

using (SqlBulkCopy BC = new SqlBulkCopy(myADONETConnection))

Full code

#region Help:  Introduction to the script task
/* The Script Task allows you to perform virtually any operation that can be accomplished in
 * a .Net application within the context of an Integration Services control flow. 
 * 
 * Expand the other regions which have "Help" prefixes for examples of specific ways to use
 * Integration Services features within this script task. */
#endregion


#region Namespaces
using System;
using System.Data;
using Microsoft.SqlServer.Dts.Runtime;
using System.Windows.Forms;

using System.IO;
using System.Data.OleDb;
using System.Data.SqlClient;

#endregion

namespace ST_832f7aa5691848e6afb82ea66aab424e
{
    /// <summary>
    /// ScriptMain is the entry point class of the script.  Do not change the name, attributes,
    /// or parent of this class.
    /// </summary>
    [Microsoft.SqlServer.Dts.Tasks.ScriptTask.SSISScriptTaskEntryPointAttribute]
    public partial class ScriptMain : Microsoft.SqlServer.Dts.Tasks.ScriptTask.VSTARTScriptObjectModelBase
    {
        #region Help:  Using Integration Services variables and parameters in a script
        /* To use a variable in this script, first ensure that the variable has been added to 
         * either the list contained in the ReadOnlyVariables property or the list contained in 
         * the ReadWriteVariables property of this script task, according to whether or not your
         * code needs to write to the variable.  To add the variable, save this script, close this instance of
         * Visual Studio, and update the ReadOnlyVariables and 
         * ReadWriteVariables properties in the Script Transformation Editor window.
         * To use a parameter in this script, follow the same steps. Parameters are always read-only.
         * 
         * Example of reading from a variable:
         *  DateTime startTime = (DateTime) Dts.Variables["System::StartTime"].Value;
         * 
         * Example of writing to a variable:
         *  Dts.Variables["User::myStringVariable"].Value = "new value";
         * 
         * Example of reading from a package parameter:
         *  int batchId = (int) Dts.Variables["$Package::batchId"].Value;
         *  
         * Example of reading from a project parameter:
         *  int batchId = (int) Dts.Variables["$Project::batchId"].Value;
         * 
         * Example of reading from a sensitive project parameter:
         *  int batchId = (int) Dts.Variables["$Project::batchId"].GetSensitiveValue();
         * */

        #endregion

        #region Help:  Firing Integration Services events from a script
        /* This script task can fire events for logging purposes.
         * 
         * Example of firing an error event:
         *  Dts.Events.FireError(18, "Process Values", "Bad value", "", 0);
         * 
         * Example of firing an information event:
         *  Dts.Events.FireInformation(3, "Process Values", "Processing has started", "", 0, ref fireAgain)
         * 
         * Example of firing a warning event:
         *  Dts.Events.FireWarning(14, "Process Values", "No values received for input", "", 0);
         * */
        #endregion

        #region Help:  Using Integration Services connection managers in a script
        /* Some types of connection managers can be used in this script task.  See the topic 
         * "Working with Connection Managers Programatically" for details.
         * 
         * Example of using an ADO.Net connection manager:
         *  object rawConnection = Dts.Connections["Sales DB"].AcquireConnection(Dts.Transaction);
         *  SqlConnection myADONETConnection = (SqlConnection)rawConnection;
         *  //Use the connection in some code here, then release the connection
         *  Dts.Connections["Sales DB"].ReleaseConnection(rawConnection);
         *
         * Example of using a File connection manager
         *  object rawConnection = Dts.Connections["Prices.zip"].AcquireConnection(Dts.Transaction);
         *  string filePath = (string)rawConnection;
         *  //Use the connection in some code here, then release the connection
         *  Dts.Connections["Prices.zip"].ReleaseConnection(rawConnection);
         * */
        #endregion


        /// <summary>
        /// This method is called when this script task executes in the control flow.
        /// Before returning from this method, set the value of Dts.TaskResult to indicate success or failure.
        /// To open Help, press F1.
        /// </summary>
        public void Main()
        {
            String FolderPath = Dts.Variables["User::FolderPath"].Value.ToString();
            String TableName = Dts.Variables["User::TableName"].Value.ToString();
            var directory = new DirectoryInfo(FolderPath);
            FileInfo[] files = directory.GetFiles();

            //Declare and initilize variables
            string fileFullPath = "";
            string fileFullName = "";

            //Get one Book(Excel file at a time)
            foreach (FileInfo file in files)
            {

                fileFullPath = FolderPath + "\\" + file.Name;
                fileFullName = file.Name;
                
                
                if (fileFullName.Substring(0,10) == "Production")
                {
                    MessageBox.Show(fileFullName);
                    //Create Excel Connection
                    string ConStr;
                string HDR;
                HDR = "YES";
                ConStr = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source=" + fileFullPath + ";Extended Properties=\"Excel 12.0;HDR=" + HDR + ";IMEX=0\"";
                OleDbConnection cnn = new OleDbConnection(ConStr);


                //Get Sheet Name
                cnn.Open();
                DataTable dtSheet = cnn.GetOleDbSchemaTable(OleDbSchemaGuid.Tables, null);
                string sheetname;
                sheetname = "";
                MessageBox.Show("Sheet is open");
                    foreach (DataRow drSheet in dtSheet.Rows)
                {
                    if (drSheet["TABLE_NAME"].ToString().Contains("$"))
                    {
                        sheetname = drSheet["TABLE_NAME"].ToString();
                    }
                }
                    MessageBox.Show("Creating datatable DT");
                    //Load the DataTable with Sheet Data
                    OleDbCommand oconn = new OleDbCommand("select * from [" + sheetname + "]", cnn);
                OleDbDataAdapter adp = new OleDbDataAdapter(oconn);
                DataTable dt = new DataTable();
                adp.Fill(dt);
                cnn.Close();

                    MessageBox.Show("Excel connection closed");

                    //Use the ADO.NET connection and Load the data from DataTable to SQL Table
                    SqlConnection myADONETConnection = new SqlConnection();
                myADONETConnection = (SqlConnection)(Dts.Connections["DMDSQL"].AcquireConnection(Dts.Transaction) as SqlConnection);

                    MessageBox.Show("SQL Connection is open");

                    using (SqlBulkCopy BC = new SqlBulkCopy(myADONETConnection))
                {
                    BC.DestinationTableName = TableName;
                        foreach (var column in dt.Columns)
                        {
                            if (column.ToString().Substring(0, 1) != "F")
                            {
                                MessageBox.Show("Exception Column, Mapping " + column.ToString() + " to F1");
                                BC.ColumnMappings.Add(column.ToString(), "F1");
                            }
                            else 
                            {
                                MessageBox.Show("Regular Column: " + column.ToString());
                                BC.ColumnMappings.Add(column.ToString(), column.ToString());
                                //BC.WriteToServer(dt);
                            }
                            MessageBox.Show("Writing DT to server");
                        }
                        BC.WriteToServer(dt);
                        //if(column.ToString.Substring(0, 1) != "F")
                        //{

                        //}
                        //else
                        //{
                        //    //BC.ColumnMappings.Add(column.ToString(), column.ToString());
                        //    //BC.WriteToServer(dt);
                        //}

                    }
                }
            }

            Dts.TaskResult = (int)ScriptResults.Success;
        }

        #region ScriptResults declaration
        /// <summary>
        /// This enum provides a convenient shorthand within the scope of this class for setting the
        /// result of the script.
        /// 
        /// This code was generated automatically.
        /// </summary>
        enum ScriptResults
        {
            Success = Microsoft.SqlServer.Dts.Runtime.DTSExecResult.Success,
            Failure = Microsoft.SqlServer.Dts.Runtime.DTSExecResult.Failure
        };
        #endregion
    }
}

I've put try catch around everything and the error remains the same. Runs perfectly every time in a standalone package.