VB.NET mouse_event move error en destino

Private Declare Function apimouse_event Lib "user32.dll" Alias "mouse_event" (ByVal dwFlags As Int32, ByVal dX As Int32, ByVal dY As Int32, ByVal cButtons As Int32, ByVal dwExtraInfo As IntPtr) As Boolean

<DllImport("user32.dll")>
Private Shared Sub mouse_event(dwFlags As UInteger, dx As UInteger, dy As UInteger, dwData As UInteger, dwExtraInfo As Integer)
End Sub

Private Sub Button1_Click_4(sender As Object, e As EventArgs) Handles Button1.Click
    mouse_event(MouseEventFlags.MOUSEEVENTF_MOVE, Convert.ToUInt32(txtx3.Text), Convert.ToUInt32(txtx4.Text), 0, 0)
End Sub

Private Sub savex_Click(sender As Object, e As EventArgs) Handles savex.Click
    txtx3.Text = x1.Text
    txtx4.Text = x2.Text
End Sub

Private Sub NativeMethods_MouseMove(sender As Object, e As MouseEventArgs) Handles Me.MouseMove
    x1.Text = MousePosition.X.ToString
    x2.Text = MousePosition.Y.ToString
End Sub