parallel port programming

Dear Sirs

I used the following code to receive a data through parallel port...But when i run the same, i see a exception called SEH exception was unhandled External component has thrown an exception is being held...

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
Dim intAddress As Integer, intReadVal As Integer
intAddress = 378
intReadVal = Inp(intAddress)
TextBox1.Text = intReadVal.ToString()
End Sub

Pls help me in this regard...