Most likely you have an air leak on the suction side. Doesn't take much of a leak to not prime and if totally dry they may not prime either. I'm assuming this is an inground pool and the pump is above the pools water level. The crack at the valve wouldn't prevent priming as that's on the pressure side. Most likely place for an air leak is the pump basket lid. Make sure it's clean and no cracks or irregularities to prevent good seating. Also try adding a bucket of water right into the basket as suggested to 'start' the flow. If you have a total blockage on the pressure side, after the pump, there may be enough back pressure to prevent priming also but this is a long shot. If you throw your valve to 'waste' that is a direct path from the pump to the waste line bypassing the filter so you may try that position and see if it will prime.
Al