help from LJ

[Cal]

running play past the line. ball goes forward from the runner to a blocker. about three yards. i, being the umpire only see the ball going forward. i have no idea if it was a pass or a fumble. i throw a flag at the spot where the ball becomes loose. after the ball is dead the LJ said that the defender knocked the ball loose and that it was a fumble. we wave off the flag and mark the ball ready for play. The A coach is fine with the call. not so with the B coach, he thought that any ball going forward in the air was a pass.