errorProvider1 does not contain definition and no extension method

Question

I just started learning C# and started with Windows Forms project. When I try to validate text fields I get this error:

Error 1 'Downloader.SDownloader' does not contain a definition for 'errorProvider1' and no extension method 'errorProvider1' accepting a first argument of type 'Downloader.SDownloader' could be found (are you missing a using directive or an assembly reference?) C:\Users\Bad_Wolf\documents\visual studio 2010\Projects\Register\Register\Form1.cs 77 22 Register

There is my source code:

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;

namespace Downloader {
    public partial class SDownloader : Form {
        public SDownloader() {
            InitializeComponent();
        }
        private void fname_MouseClick(object sender, MouseEventArgs e) {
           fname.Text = "";
        }
        private void fname_TextChanged(object sender, EventArgs e) {

        }
        private void lname_MouseClick(object sender, MouseEventArgs e) {
            lname.Text = "";
        }
        private void lname_TextChanged(object sender, EventArgs e) {

        }
        private void username_MouseClick(object sender, MouseEventArgs e) {
            username.Text = "";
        }
        private void email_MouseClick(object sender, MouseEventArgs e) {
            email.Text = "";
        }
        private void password_MouseClick(object sender, MouseEventArgs e) {
            password.Text = "";
        }
        private void password2_MouseClick(object sender, MouseEventArgs e) {
            password2.Text = "";
        }
        private void password2_TextChanged(object sender, EventArgs e) {

        }
        private void register_Click(object sender, EventArgs e) {

        }
        private void fname_Validating(object sender, CancelEventArgs e) {
            string errorMsg;
            if (fname.Text.Trim().Length < 4) {
                e.Cancel = true;
                fname.Select(0, fname.Text.Length);
                this.errorProvider1.SetError(fname, errorMsg);
            }
        }
        private void fname_Validated(object sender, EventArgs e) {

        }
    }
}

Answer 1

The reason you are getting this error is because you haven't added the ErrorProvider to the form in the design view. Add the ErrorProvider and name it errorProvider1