It is possible to install the disc backwards (front-to-rear), in which case you won't have enough adjustment, and the clutch will not release properly. The disc should be marked with the flywheel side. If the disc is not marked, I believe the offset on the center hub goes into the pressure plate. The other possibilities mentioned by others also exist, but my first thought is that the disc is backward. Regardless, I think you still have to disassemble everything to find the cause of your trouble.

Harvester