3-Minute Game Error

I played a 3-minute game today. Wasn't the best game I've played, but I was ahead on time, and I eventually managed to get this position:

My opponent's time then ran down the final second and a half to 0:00.0, and I expected to be awarded the win. However, the game - for whatever reason - was declared a draw on account of insufficuent material. Pawns can promote, so this makes little to no sense to me. Does anyone else know why this happened?

YOU can't win with insufficient mating material on time! Start reviewing the basic rules and laws of chess you'll be glad you did.

NizmoRoy said

"YOU can't win with insufficient mating material on time! Start reviewing the basic rules and laws of chess you'll be glad you did."

Do you need ice for that burn

so how exactly were you planning on checkmating your opponent if he/she hadn't ran out of time?

http://www.nytimes.com/2008/06/10/health/10real.html

Your opponent can't win because he doesn't have time.

You can't win because you don't have material.

Therefore: draw.