homerun with one runner on base

Question
we had an incident where the opposing team had a player hit one over the fence with one runner on first as the lead runner rounded third base he stopped and let the player behind him catch up to highfive before either one crossed the plate.we appealed to the home plate umpire for automatic out he said and i quote"show it to me in the rulebook and i will make the call"otherwise both players are safe.this is a 11/12 year old littleleague division.
any input would be greatly appreciated.

thank you,
don fornataro

Answer
If the player who hit the homerun scored before the runner on base then the base runner would be out. I cant think of any reason why a coach would let this happen. The umpire, however, should know the rule and never say what he said to anyone.

If the runners realized what they did and corrected it before scoring then its fine. I would ask for a league official to talk to this umpire about that one. That is something that should never be said.