I downloaded some halo 3 maps and i cant access them on other accounts?

[teh blarg]

i have downloaded the halo 3 map packs 'Legendary' 'Heroic' and 'Cold Storage' and i cant play game types that need the legendary map pack. i check in my memory and they are all there but when i go into halo 3 i cant use any of the legendary maps (i have used them before but it they dont work most of the time). Also, when i was able to use the legendary maps i couldnt play them on my other accounts but the heroic maps still worked for them. Any one know why the legendary maps dont work or why my other accounts cant use the map pack?