Call of duty 4: variety map packs.?

[gboy]

I have one question about the map packs i boght for call of duty 4 the other day. i just for some reason can't play all the map packs. i mean yea like i can play them. but they almost never appear. like if i go into a hardcore S&D . 9/10 the map packs won't come. like is there a trick or something so i can play those maps more often besides in private match's i can play those in private match's all i want but during public matches i can barely get to play them so any help would be great.

Thanks.