Hi, Dennis
Looking through your previous post's, Gecko's and CNC4PC your double opto-isolated, Have you try-ed increasing your Step's, Dir., Pulse's to 5 under Motor tuning, If its at 0 there may not be enough delay time there for both opto's to see the pulses.
As far as your Vel & Accl, Set them low values (v, 50, A 10 or so), Adjust the Steps Per till there accurate, Then increase Vel to a speed your confortable with or loosing steps then back it off some, Then increase the Accl up the same way and back it off also.
Is this stepper or servo system ?
Hope this Helps, Chip