Philips hue lightbulb dimmable possiblity

I am new to this openHab. I have bound philips hue bridge to my openhab (that runs on a raspberry pi).

I have also added all controls that it wants to import as things when adding. But somehow I am not able to dimmer my lightbulbs.
Is there something I need to do to get that working? Or does it not work with openhab?