Elektron Musical Instruments

I have Cubase 5 as the master clock for the MD. 
Everytime Cubase runs thru a midi part, the MD plays
the wrong Kit or i can hear notes playing that are not in the 
patterns.
I can't figure out why this is happening.  I have tried Cubase as 
theMaster clock with other synths and samplers and never had 
this problem.

Can someone please tell me what's wrong,

Thanks,

Simon