King+Knight vs King+Bishop?

Hi, I recently played a game against an opponent where I had only a king and knight remaining, and my opponent had a king and a bishop. This was a 20 minute game and there was still more than 10 mins remaining on each clock. Now, once the exchanges had been made, I didn't even consider that it wouldn't be a draw, since mate can't be achieved with either a lone knight or lone bishop. Yet, the game didn't end...I offered my opponent a draw but he declined, yet within the next few moves he took my knight and then the game was drawn due to insufficient material...

So, it seems that if he wanted to, he could have had it that we moved our pieces about the board for 20 minutes and try to beat each other on time, as I can't see how mate could be achieved (unless they play very poorly). If someone has the answer, can they post a scenario leading to theoretical mate with the same or similar setup?

Edit: I just realized that the 50 move rule would probably apply in this case. But that the game doesn't just end with these pieces seems pointless, unless one of the two happens to be in a position ready to be mated, which seems very unlikely, though perhaps possible.

I had a similar situation in a 5 min game. There was a move repetition draw, but nothing happened. Like we played the same moves for 15 times and no draw. The opponent, naturally, refused my draw a couple of times, so I lost on time after my last minute ran out.

Without pawns, it's a draw. With pawns, it depends on the position of the pawns.

NB: You can even let your opponent capture your knight/bishop for fun. Pretend you are pissed. It will still be a draw.

By the way, you must click "draw button". 

What site/server were you playing at?  Here at chess.com?

I suppose if it was not declared a draw automatically, is because it's still possible for Black to mate White.  Here is the final position:

I'm sure some sites (FICS and ICC, I believe) will automatically declare that original position as drawn.

just move your Knight next to his King or some place where it can be taken.

This may or may not solve the problem.

Polemida said "He lost on time". But if you lose on time then you can appeal the arbiters that this is a draw because of insufficient material.

and White to mate Black!!!

Bishop + king can mate king + knight:

The bishop should be on g7 in that diagram

Typical I've just edited my post it to that same configuration:D!!

anyway thanks pfren for spotting that mistake:D

Of course the K and N can mate also--so in that sense there is mating material left--so I guess just repeat moves and get to 50 moves or 3 fold repetition before time runs out.