Hi everytime i enter my arrival the FMC just says <ACT> nothing i can do to change it? Any ideas? Cheers Mark

People that can help are goin to need to know what arrival for what airport.

did you get the message in the CDU? "PROGRAM PIN ERROR" (FMC connector wiring is incorrect.System unusable; advise maintenance personnel. The CLR key will not clear the message.) try the other CDUcheck your failures

Yeah i did get that message. But then when i tried using the other CDU it wouldn't allow my arrival runway.

i had something similar to this once. Had you already flew all the legs of the flight ?

Returning to EGBB from LEIB soon as i try to enter the arrivals page for EGBB a screen comes up saying FMC <ACT>