Ok, a recent problem was getting a chopper to land using the heli land "GET OUT" then a command to disembark all the soldiers. It worked perfectly in the mission preview but in the mission it never landed and just kept going on its merry way lol....
First off, if you are asking specifically about MP then post on MP board.
Did this problem happen when the MP mission was on a server? If so how exactly did you give the heli land "GET OUT"? The command must be executed where the heli is local. If the AI heli is not in a player group then it is local to the server. If it is in a player group then it is local the machine of the group leader.
A mission often does not behave exactly as in the editor, both when exported to SP and MP. You can do some very limited testing of MP issues by playing with your own machine as a non-dedicated server. For full MP testing you need a dedicated server and a lot of patience.
The best approach is to ask a specific question on these forums with the exact details of what you are doing- even better upload a mini demo mission of the problem.
Even if you do not script, take a look at Mandoble and Spooner's MP Scripting Tutorial in the ED for some answers about locality.