[2005][RESOLVED]WindowFromPointXY

[edwinho]

Private Declare Function WindowFromPointXY Lib "user32" Alias "WindowFromPoint" (ByVal xPoint As Long, ByVal yPoint As Long) As Long

Private Sub Timer1_Tick(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Timer1.Tick

Dim ptx As Long = System.Windows.Forms.Cursor.Position.X
Dim pty As Long = System.Windows.Forms.Cursor.Position.Y
Dim OnhookWindow As Long = WindowFromPointXY(ptx, pty)
If OnhookWindow <> Me.Handle Then
DoSomething()
End If
End Sub

i got the error message "Unmanaged code debugging" ? What is this?
What Wrong With My Code?