I'll go along with what Dan stated, if you had the receiver apart including the rotary bolt there is a good chance you didn't put it back in the right position.
Attached to the top lever is the coupler which has a pin on the end, that pin fits into a hole in the rotary bolt (you can see the hole in the side of the rotary bolt) that lets the coupler rotate when the top lever is moved. If not in that hole you will bind it up and the top lever will not move.