Posky CRJ-200 airspeed

I recently started flying the Project Opensky CRJ-200 in FS2004, and I've tried two different add-on panels ("crj200_pnl.zip" by T. Costa and "replacement_project_opensky_crj_panel.zip" by M. Leegard). The airspeed/IAS hold and Mach hold don't seem to work above roughly 220 knots. That's as fast as I can go. Below that speed, the autopilot's airspeed hold works great. The operating manual that comes with the Posky CRJ indicates you can get up to Mach .74, but I've tried everything including arming and activating the autothrottles, and I can't increase the airspeed above approximately 220 knots using the autopilot. I'm also going to post this question in Posky's forum. Thanks in advance for any suggestions.