Likely a stupid question (hence the reason it likely has not been directly asked)...
Is there any water flowing over the biowheel? (Basically, is the pump turned on and is it flowing water to the bio wheel?)
If the water is flowing, how much is flowing? Can you get any sort of measurement, and is that measurement anything close to the specs for the filter?
What about filter material? Is the filter material positioned in such a way as to alter the flow of the water? What if you totally remove the filter material, does that get the wheel turning? Or if you have not inserted the filter material in the filter, is the filter perhaps spilling "under" the wheel and the solution is to get the filter correctly installed?
Otherwise, at this point, pictures would be a big help.