Why can't I join a Halo 3 party?

[Ryan D]

First off me NAT is open. I can join COD4 but not Halo 3 whats up?
No I did not save the game on my hard drive the only game I saved was Call of duty world at war.

 

[parker_hm]

Halo 3 has a tendency to spazz on that. did you download the game onto your hard drive? if you did then way to go because you shouldnt download halo 3 to your hard drive. just wait awhile. the case may also be if you dont have all of the maps that have been released and you tried to enter a map where someone was playing a map such as blackout.