Or it is possible that the game ended in less than ~10 moves (I forget the exact number, but I believe that if you win before a certain number of moves have been played, there will be no change). I know that what I just mentioned is true for timeouts, but I'm not sure about checkmate.

Was the person you beat rated much lower than you?  It is possible if the difference is great enough, that the win will not cause your rating to go up.  But, this should be a difference of hundreds of points.

Thank you all for your response and help.

It was a rated game.  But I saw my score go up after my last win, so it seems that the system is working.

if that's the case it was probably because the opponent had a significantly lower rating compared to you, or simply, the game was unrated...

hmmm...by score u mean rating i suppose?

sorry further information to that, scroll down to "contact us" and tell them what has happened and they should rectify it for you

your rating will not change if it was an unrated game but if it was a rated game, you can go to "help" at the top of this page and you should get answer.