oops, left runner on!

[kchamp]

It shouldn't happen, but it did. Now what?

Sit: Little League tournament game. Runner on first, one out. Three man crew.

Batter hits to third baseman who throws to 2nd base for the force out on the lead runner. Close play and umpire is in position for the play, but doesn't signal after the dust clears and trots off to his position. Both managers assume the runner is safe, and the runner stays at 2nd. A subsiquent play allows that runner to score. No problem. But upon the next out, it comes to light that its 3 away.

Understandably, the offensive manager wants his score to count. A protest is lodged at this point. Since this is a local tournament, protest don't go beyond the tournament director, and she rules the run doesn't count.

Is there some precedent out there to rule on this bizare situation?