Mistake in Tactics Trainer

Is there a place to officially submit a mistake in a tactics trainer problem? I'm posting here because I didn't see another means of reporting it.

http://www.chess.com/tactics/?id=330891

That tactics problem has a mistake in the solution. I added comments to explain in the problem.

The problem isn't incorrect because it shows why black can't take the knight at the end. Tactics Trainer will often do that to show why a certain move doesn't work. This is especially educational in low-level problems like this one.

Oh, now I understand.

So, you are saying that it judges your moves (white in this case) to see if they are correct. But the computer opponent (black in this case) will sometimes deliberately make a mistake to see if you can make use of it?

That actually makes sense. Thanks for the comment.

I just assumed that all moves in tactics trainer were optimal. I thought you were supposed to find the "forced" good line assuming best play against you. But, maybe that isn't always true. Good to know.

If all moves, were optimal, some people wouldn't see the immediate point (some still don't).