Eric,
Make sure that the axis mapping is setup in the plugin. Yoiu need to set it even if you do not want to re-map an axis. So set x axis to x, y to y etc. Also exit and restart Mach to get everything loaded properly. Then make sure that you are wired to the primary encoders for the axes when connecting to the ICM 2900. The encoders box should be unchecked. Please call or e-mail me if you still have trouble.
Kenny