Mpc2000 drum machine, as master midi sync, to cubase

I use my Mpc2000 drum machine, as master midi sync, to cubase the slave while Record my Keyboard modelers sound to cubase I have been recording this way for a year now but for some reason it have stare to acting weird sometime i stared my drum machine and cubase 5.0 will stare to record, and some time its stare and stop but now i cant get cubase to stare to record at all. But it will sync and work if I use cubase5.0 as master sync to my MPC drum machine.
the reason i like to use my Mpc2000 drum machine as the master its keep cubase sync better when iam recording my Keyboard modelers sound. can anyone give any help on this i will be very thankful

It's usally better to use the end of the recording chain, in this case your multitrack software (cubase) as the master sync. When you use 2 inch tape, you stripe smpte code on a track of the reel, and output the playback of that code to all necessary machines.
Also, I have followed this standard in the digital world, because most manufacturers DAW software are terrible at handling incoming code, but pretty solid at being master to other machines.

Are you sequencing your synths w/ cubase, or with the MPC?