Why is that happening though? This kink of malfunction comes up quite a bit especially when the kits are cheaper or there is a higher demand (more junk gets through). If the FCG springs are installed incorrectly the FCG won't work correctly. The disconnector spring in particular is often installed upside down. The bottom of the spring is supposed to go in the trigger pocket to make it stay in the trigger when the trigger or disconnector is removed. If it is placed in upside down the wider section will lock into the disconnector and trigger pocket and hold the disconector back or cause it to be "sticky" so it occasionally doesn't work. Also if the disconnector pivot hole is off slightly the disconnector may not pivot forward enough to grab the hammer. There is a fitting tab on the front of the disconnector that will allow for some adjustment to gain a little more contact with the hammer. No sense buying new parts if you don't need them.