You can also activate a log, to see what's happening: open the Notepad and type the following on a new blank file:
logFile=couatl.log
(please note logFile is written beginning with a lower case l and a capital F )
Save the file as couatl.ini in the FSX\fsdreamteam\couatl folder, so it stays at the same level of the couatl.exe. Then go in FSX, select a boarding or deboarding option, let it finish, then exit from FSX and post the content of the Couatl.LOG file that should have been created inside FSX\fsdreamteam\couatl