Using statements not recognized in a class

See more:

C#

I am trying to write a thread that will load data into a winform while other processing continues in the background. I have put the definition of the thread class in a separate file in the project - Thread.cs. Here is the code in that file:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Threading;
using System.Diagnostics;
using System.Windows.Forms;


namespace Thread_Test_Sending_Data_to_Thread_Function
{
    using System.Windows.Forms;

    public class Thread1
    {
        

        private delegate void SetLabelTextDelegate(FormData InputClass);
        public void FormWriteMethod(FormData InputClass)
        {
           

            if (this.InvokeRequired)
            {
                this.BeginInvoke(new SetLabelTextDelegate(FormWriteMethod), new object[] { InputClass });
                return;
            }
            TestLabel1.Text = InputClass.Label1Data.ToString();
            TestLabel2.Text = InputClass.Label2Data.ToString();
        }
    }
}

I know the definition of InvokeRequired is in System.Windows.Forms. The reference works in the main body but when I try to reference InvokeRequired or BeginInvoke in the Thread.cs it isn't recognized even though I have used System.Windows.Forms. None of the using statements in the file are recognized.

What is going on?

Thanks for any help,

Andy Cruce

What I have tried:

I have tried referencing the Invoke methods in the main body and it works fine. Have also tried a similar reference in other small class files with the same result - namely it doesn't look like the using statements are recognized.