Sorry if this has been discussed before on the forum but I was playing a 5 0 game on live chess - http://www.chess.com/livechess/game.html?id=5742745 - when I ran out of time but my opponent had only a knight left, so I can't be checkmated, therefore the result should be a draw, shouldn't it? 

The problem is that YOU have enough material left to mate your opponent, therefore the result is correct.

White had enough material to checkmate.

He could still technically mate you.  Consider the following sequence:

Now, this probably isn't the quickest helpmate, and it does require you to pretty much walk into it, but it is sufficient to show that White can checkmate Black from the actual game-end position.  If any such legal sequence exists, regardless of the quality of the moves, then it isn't a draw, but rather a loss on time.  Sorry to say, but the result is accurate.

Although unlikely, It is probably theoretically possible for your opponent to checkmate you because of the extra pieces that you have on the board.

Thank you guys! All the answers sound logic to me!

When you're low on time and you cannot win for sure, just clear his board with the remaining time (you MUST clear his board.) and it'll be a draw at worst (unless you disconnect.)

And from all posts above, you can get a help mate, lol.

Yeah right. why is not a draw?