%xl|c|FastForward|50|50|
%xl|d|FastRew|50|50|
I just noticed that the ffw & rew images don't have the .bmp extension, they should be
%xl|c|FastForward.bmp|50|50|
%xl|d|FastRew.bmp|50|50|
That is something that has to be corrected for sure.
If you ask in the forums for help on your code, people will logically tend to check if the code instructions themselves are wrong; since this problem is not code related, you could have noticed it yourself by just checking more carefully
Note:
Not that it is related to your problem, but
when you get your WPS working, after that, check examples 1 (what you've done) and
1a (what you could do) here
http://www.rockbox.org/twiki/bin/view/Main/CustomWPS#Images , to learn the use of bitmap strips, it's a very useful concept, and it seems to apply perfectly to your design, since you are using four changing images (play, ffw, rew, pause) that go in the same position.