I was attempting to post a diagram as a comment in one of the Tactics Trainer puzzles.  I wanted to start with the board from the puzzle. 

What I found is that the FEN string given in the "Analysis and Source" page was not a valid FEN string for input into the diagram creator.

Here is the string that I copied from the Analysis page:  "4r1k1/1b2rppp/p2p2n1/1ppP4/1P1R1P2/N1PB4/P5PP/5RK1 w - c6"

Is this a problem with all Tactics Trainer pages, or perhaps with the diagram editor?  If so, it would be nice if the FEN strings were somehow fixed to cooperate better with the diagram editor, because there is no move list to import either and it is a bit tedious to recreate the board from scratch.

Maybe the best solution is just to understand FEN a bit better so I can fix the strings myself.  Any input is appreciated!

Hmm, very strange. It appears the Chess.com diagram editor does not recognize this FEN string. However, when I put this FEN string into my Rybka Chess program it recognizes and loads the FEN string without problems.

I will forward this on to the Chess.com team for investigation.