tactics trainer

I know there have been countless threads on tactics trainer.  I think its great I use it for hours a day sometimes.  However I do have one gripe with it.  If anyone can explain this to me that would be great.  I don't understand why when you get a tactic correct it awards you less points than it takes away when you get the problem wrong.  I just did over 20 problems just now and each one I get wrong I lose up to 15 points sometimes and when I get it right at 100% it only awards me 8-10 points.  What gives.  I feel like I'm never gonna break 2000 on this thing at this rate.  It's not a big deal.  I just feel if you get a 100% on the problem it should award you the same amount of points that it would take away  if you got the problem wrong.

depends on what rating the problem is in relation to your rating at the time.  not totally sure though, if you're solving the problem on 100% you should be getting good rating points for it