Just had the oddest thing happen to me when I sent a runner home from second base on a single to centerfield. The basehit resulted in a close play at the plate. I tried to advance the runner on first over to second after the centerfielder made the decision to throw home, but then decided not to. Here was my downfall. In doing so I accidentally sent both runners (instead of just the runner on first) back to their bases. But a collision had already occurred at the plate (even though the runner looked like he was still a few feet from homeplate), jarring the ball loose and the announcer scoring it as a run. To my surprise, the run was not counted, the runner coming home disappeared from the field, and no out occurred. Just very bizarre!!
I had a similar thing occur to me yesterday. Runner on third, batter hit a slow grounder to 2nd. I started my runner towards home, hoping to draw the defense to him (it worked). I over-committed however and got caught in a hot box. Then, being the clumsy oaf that I am, I sent him towards home when he should have gone back to 3rd. The SS and catcher collided after the SS threw the ball, the announcer called it a run, but nothing showed up on the scoreboard, there was no out registered and the runner was gone from the field. Weird stuff!