Magazine won't work for my agm 614?

i just got my new agm hk 416/614 today, and it came with a magazine that is pretty good, but i also already owned a dboys m4 metal hi cap magazine too, which i though would be fine because the 614 takes all m4 parts and stuff, but when i put the magazine in, every few shots if i wiggle it around a little i can hear the little button you pull back to release bbs going, so more bbs get in, why isnt it just staying pushed? what should i do??