Two things you might try:
1. Switch the "PGM=" setting to the type of data you are trying to send it (i.e. "Patch" if you're sending a patch data dump, or "Multi" if you're sending a multi data dump). Theoretically, this should not matter, but it might...they mention doing this when transferring from one K5 to another. NOTE: I've never had to do this with mine.
2. Be sure and exit the MIDI system screen so that you see the current patch name. When my dumps are successful, you can see the patches change as they are received by the synth. If you're still in the MIDI system screen, this might prevent this from happening.
I remember going through hell getting my patch dumps back and forth to go well (my solution ended up being the timing setting of my editor/librarian, MIDI Quest).
Keep or toss,
J.D.