Cannot Record on MPC 2000

I'm trying to use it with a synth. I can play previously made sequences, but cannot record new ones. Everything appears to be hooked up correctly. Any clues?

your saying that you already recorded a sequence WITH your synth but it wont let you record anymore??

Yes. I have not used the MPC 2000 for a while. It will play back the sequences that I previously recorded, but if I try to record a new sequence, there is no sound, so the problem lies somewhere in the recording process, and not the playback.