Default dpad in tomtom navigator 5.21 no more zooming maps

Hi again,

as I am using tomtom navigator 5.21 now, I have noticed that if running smartkey the maps on tomtom will no more zoom-in or out with dpad but instead the sound volume will increase or decrease. If smartkey is deactivated tomtom runs as it should and dpad makes the maps zoom-in or zoom-out. Can you fix this bug?

TIA