Analogue-sequencer

I can't seem to get my two P3's to stay-in-sync, my second one
(slave P3) always seems to be 1 or 2 steps in front of the master 
P3 sequencer.

I have midi-clock set to 'on' on the master-P3 and midi-clock off
on the slave P3 unit.

How do i keep them both sync'd either during a start/stop operation.


Best,
A1k