There is no line trace in your screenshot. But if the line trace is inside of your OnFire event it will probably only be called on the server and therefore you will not see it on a client if you are using the DrawDebugType enum. If the line trace is colliding with something it is probably your character or the weapon.
Also remember that the multicast event fires on all clients and the server. If the OnFire event also calls the MulticastFire event you are causing some unwanted loop behaviour.