sorry if there is a post about this already, i did not see one

I'm looking at my tactics training score, which has gone down despite not failing a puzzle. I had a 1268 rating, completed puzzle 21811 at 60% + 30 but ended up with a rating of 1244 (a minus 24 points instead).

I'm just pointing this out if it's a bug or to see if i'm missing something in the scoring.

This is becuase although you were able to figure out the problem, based on the time that it took you, you only scored 60 % of what was available, nearly a draw, statistically speaking. The amount of time it takes you to finish a puzzle is heavily factored into your score. You can read more about the ratings and the Tactics Trainer here: http://www.chess.com/tactics/help.html.

ah - thanks. I assumed that the score given took in account time.