Bob,
Since the autopilot would accept steering commands from the 5600 (alt and heading) but would ignore the any internal flight plan in the 5600, I suggested the RS232 as a cause for the problems over 3 months ago, but I was told everthing was wired correctly and working properly and I just didn't understand how to use it.
Thank you for getting involved. Without you help I don't think the planes problems would ever have been resolved.
Art