Thread inside module and add value into me.texbox1 - vb.net

Question

Have anyone idea why my code return "" inside my Textbox ? :-)
This i have in main Class
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button2.Click
Dim My_Thread as Threading.Thread
My_Thread = New Threading.Thread(AddressOf Module1.MyTest)
My_Thread.Start()
End Sub
And this in module1
Sub MyTest()
Dim TestingValue as string = "Test"
MainForm.Textbox1.Text = TestingValue
End sub
Invoke all time crash code and another try return "" inside texbox1 :-/

Answer 1

Create a Sub Class with public declarations to any object you want on MainForm, then pass the class as a parameter to the module. This would be a cleaner approach than passing the entire Form class instance. Then using the method that Jimi has suggested you can setyou textboxs without cross thread violation.
Public Class MainForm
Public Class PassToModule
Public TxBx1 As TextBox = MainForm.TextBox1
Public TxBx2 As TextBox = MainForm.TextBox2
End Class
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
Dim PassToModule As New PassToModule
Dim My_Thread As Threading.Thread
My_Thread = New Threading.Thread(AddressOf MyTest)
My_Thread.Start(PassToModule)
End Sub
End Class
Module Module1
Dim FromMainForm As MainForm.PassToModule
Sub MyTest(PasToModule As MainForm.PassToModule)
FromMainForm = PasToModule
FromMainForm.TxBx1.BeginInvoke(New MethodInvoker(Sub()
FromMainForm.TxBx1.Text = "Test"
FromMainForm.TxBx2.Text = "Test"
End Sub))
End Sub
End Module