WS15Z-1 Will not dim. has any one been having any issues with it

I Recently bought few Nutone z-wave switches has the WS15Z-1controller on them. the box said they are dimmable and when i paired them with openhab it did give me a switch and the dimming option. The switch works flawlessy and was able to control with amazon echo no problem how ever the dimming option doesnt seem to be working and cannot get to work it at all. just wanted to know if any one have been having this issue. when i searched the problem i saw a few threads on WS15Z-1 but non that was related to the dimming feature.
Thank You in advance