Not sure what you mean by "it didn't fire". Did the trigger reset and the hammer activate, but simply did not set off the primer? Or was it a case of the the hammer not activating at all-that is no trigger reset. Or did the hammer go back, but not fall?
If the trigger did not fully reset, then you likely need to remove a small amount of material from the front of the grip cut out to let the trigger move forward a bit more to fully reset. However, if the trigger reset, and activated the hammer, but the hammer did not fall, then you need a touch more over travel. You will need to remove a small bit of material from the back of the trigger in accordance with Pops instructions to allow proper over travel and tripping of the sear so the hammer can fall.
Jim R