KJ Works m1911 c02 GBB

[matas17]

So iv had my KJ Works m1911 c02 GBB for a while now but i have an issue. Every time i load and fire the pistol slide lock engages and lock the slide back even tho the megazine is in with bb's in it. So i have to manually hold down slide lock down with my thumb to cycle the pistol properly. Does anyone have an idea what could be wrong.

Few days ago i cleaned pistol and relubbed the pistol with silicone oil including all the rubber o-rings.