[2005] textbox Focus

[s021126]

I want to move the "focus" when user press up down left right.
I write the following code in keydown event.
But it can't work. The left and right has no problem, however, up and down can't work.

Select Case e.KeyCode
            Case Keys.Up
                If x > 1 Then
                    x -= 1
                End If
            Case Keys.Down
                If x < 9 Then
                    x += 1
                End If
            Case Keys.Right
                If y < 9 Then
                    y += 1
                End If
            Case Keys.Left
                If y > 1 Then
                    y -= 1
                End If
        End Select
arrtextbox(x, y).Focus()