I'm not sure what to call it--as to whether it is a bug or an operator error, but I was attempting to fly MMCU to MMMZ, and the flight plan was successfully submitted. However, as following procedure, I logged on through Monterrey Center (MMTY), but I got the following message:
Thinking I had made a mistake, I attempted to log in as Mexico FIR (MMEX), Mazatlan FIR (MMZT), Mazatlan Oceanic (MMFO), Merida FIR (MMID), and then with KUSA (just out of a wild guess).
All of them, except for KUSA returned the same error code, while KUSA came back with "flight plan not held."
Is there a different FIR that I should be logging on to? And, if that's the case, is there a listing of FIRs that accept CPDLC authority?