There is a possibilty that the ball detents are allowing the ball to roll forward slightly making the gun think that there is nothing there.
Take the barrel off and look down the breach with the loader on. Turn the HALO on and look at where the ball is sitting. There may also be a problem with the HALO not feeding. If this is the case the balls may not be forced down into the breach once the first shot is fired.
Take the barrel off and look down the breach with the loader on. Turn the HALO on and look at where the ball is sitting. There may also be a problem with the HALO not feeding. If this is the case the balls may not be forced down into the breach once the first shot is fired.