OledbDataReader is not retrieving all the columns

Question

I'm have little problem in retrieving the data from a table here's the code: if the column in the db table is empty then the exception is thrown...

                string cmdText = "select member_id,disp_id,mobile_no,tm,pm,lm,due_date from Recharge";
                string UpdateStatus = "",hepUpdateStatus="";
                OleDbCommand cmdFinalUpdate = new OleDbCommand(cmdText, conn);
                OleDbDataReader updateReader = cmdFinalUpdate.ExecuteReader();
                if (!updateReader.HasRows) // this condition is creating problem
                    MessageBox.Show("No Data Pending For Updation");
                else
                {
                    try
                    {
                        while (updateReader.Read())
                        {
                            Program.MemberID = Convert.ToInt64(updateReader.GetInt32(0));
                            Program.DispID = updateReader.GetString(1);
                            Program.Mobile = updateReader.GetString(2);
                            Program.Tm = updateReader.GetString(3);
                            Program.Pm = updateReader.GetString(4);
                            Program.Remarks = updateReader.GetString(5);
                            Program.DueDate = updateReader.GetString(6);
                       }
                    }
                    catch (Exception) { }
                    finally
                    {
                        updateReader.Close();
                    }

                  }

The Problem is, it is giving error on Forth Column i.e Program.Pm = updateReader.GetString(4); the error is specified cast is not valid (actually after the 3rd column it is giving exception) but im pretty sure that casting is not the issue, coz When i remove the if condtion at the top i.e if (!updateReader.HasRows) then the code works perfectly fine, i wanna know what is the problem with that reader if m checkin' that reader has rows or not ?

Answer 1

From the GetString() documentation:

No conversions are performed; therefore the data retrieved must already be a string.

Looks like Recharge.pm is not a string or contains a NULL value.