Chris I will try and help, first make sure that the opening is clear of any debris. When you put the rotary bolt in make sure the tiny hole in the cylinder of the rotary bolt is on the upper left side. If you look close at the rotary bolt you will see a small hole drilled in it that does not go all the way through the bolt. Slip the top lever shaft down through the coupler making sure that the coupler pin end goes through that hole (look at the front of the receiver through the opening where the barrel's extension goes and looking down with a flashlight you should be able to see the coupler and part of the coupler pin.) Hold the top lever and release the trip but do not let the top lever close all the way and then try and push the top lever to open so that it stays open. If it moves with some difficulty that is ok because the top lever is not into the trigger plate housing and will be harder to move but it will move. If not the coupler pin did not go into that hole.
I hope this helps.