I'm having problems with a For Each...Next loop

[SuperSparks]

Hi all,

I'm trying to clear a load of textboxes in one go like this:

Private Sub cmdClear_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cmdClear.Click
 
        ' Clear textboxes and graphics
        Dim Txt As System.Windows.Forms.TextBox                                    ' assign textboxes to object Txt
        For Each Txt In gpbValues.Controls
            Txt.Text = ""
        Next Txt
 
 
    End Sub

I get a runtime error of InvalidCastException every time. Can anyone tell me what I'm doing wrong please?