Update Textbox from a thread

Hi Experts,

I'm trying to update a text box with a variable from a thread.  I've tried to get my head around delegates but the code below still doesnt work.

When I step through it, it seems that it fails the  Me.txtEvent.InvokeRequired() check when I would have thought it would be true.

Any idea where I'm going wrong?  BTW, this is a test project for a thread that will eventually report back at at various places in the code so I dont want to use a backgroundWorker thread.

Thanks

' Function pointer to method to update GUI
	Private Delegate Sub UpdateGUIDelegate(ByVal Bval As Integer)

	' Method to update the GUI
	Public Sub UpdateGUI(ByVal Bval As Integer)
		' Check to see who is calling this method. If other then GUI thread
		' create delegate to make the call.
		If Me.txtEvent.InvokeRequired() Then
			Dim myD1 As New UpdateGUIDelegate(AddressOf UpdateGUI)
			Me.txtEvent.Invoke(myD1, Bval)
		Else
			Me.txtEvent.Text = "A=" & Bval
		End If
	End Sub
#End Region


The code that the thread runs (in a seperate class)
	Public Sub WorkCount()
		While intA < 10000
			While intB < 100
				intB += 1
				System.Threading.Thread.Sleep(50)
			End While
			Form1.UpdateGUI(intA)
			intB = 0
			intA += 1
		End While
		intA = 0
	End Sub