my cousin bought the two new map packs for halo 3 but he cant use them will

[Lewis]

playing some games online ? can some one please help out

 

[Jay]

always happens to me
step 1: go to forge or custom games
step 2: go to map selection and then it should load the maps if not turn off ur xbox and try it again
step 3: go to matchmaking
it always works for me