'does not cock' meaning the the bolt will not go back or meaning when you cock it, the sear doesnt engage?
Try switching stocks and see if there is a difference. Will tell you if that you may may need to tighten the stock down more to engage that trigger group with the body and get the sear to engage. I dont recall if it was a Disco or another gun where that for whatever reason, I failed to have the trigger group secure enough to get sear engagement when cocking. Easy fix, after figuring out the cause.