I have the same problem. I was a United 767-300, departing Frankfurt for Washington Dulles, and I was IFR. I did everything on the Shift+6 Panel(Overhead), and programed the FMC. Franfurt departure then told me (after I took off,) to turn to 265 degrees, and climb to 6,000. I entered the info on the A/P panel, and nothing happened. Heading, Armed. Altitude, Armed. Auto-Throttle speed hold, Armed. Nothing happened.  I turned on A/P CMD, and nothing happened. It was relly dissapointing, because I then had to do everything manually, and it wasn't easy. Please help! (The FMC, however, worked fine)