I just installed a shower stall in the basement. When is turn the water on (single handle diverter) all I get is hot water. I took off the handler and diverter cover as well as the part that turns to allow the water flow. When I turned on the hot water it rushed out without problem. But the cold will not flow (I open the screw for water flow). The water works fine for the sink and commode. Please assist. Thank you.

Do you know the brand and model of the valve or can you post a picture?