You camera bottom needs to be serviced. Cock, release, and film advance are all coordinated under the bottom plate. The mechanism is generally straight forward but if it is gummy then things malfunction. There is a very small "pallet" device that concludes the film advance and shutter cocking stroke. If it is gummy and doesn't seat correctly then the cycle is not completed. That is most noticeable when using a motordrive as it just locks up. There may be other parts where gummy interfaces cause different problems, such as the one you describe. You don't want to read this, but a professional overhaul would likely get you back in business.