damn thouse crickets

ello all quick question.... I'm new with keeping reptiles and I picked up a critter keeper or something along thouse lines that I figured woudl hold the crickets in there... i put in some egg carton pieces and a peice of potatoe I have two containers one for mealies and one for crickets... well on friday night a cricket got out of the keeper.. i looked at it and saw no where i thought they coudl get out... the grate on the lid that lets the air in i thought was to small for them to get out... yesterday there was another escapee and one went from the cricket one and ended up somehow in the mealworm one??? I have NO clue how they did that as i cant even figure out how they get out let alone back in... whats the *best* way to keep crickets so they dont get away like this?