using a unequipped weapon

got a prob. In backpack 1 i have m4a1tiger, ruger bisley & 3 granedes. backpack 2 - in storage i equip awm camo, de & granede. when in game i switch to backpack 2, instead of awm camo, char pulls mg3camo skull (or someting like that name), i immidietly catch game error & crash to lobby. I got mg3camo skull in loby but didnt equip it. Tried to swith backpacks a few times(each time i entered a room after crash), tried to equip/unequip awm camo with mg3camo skull. advices ?