I see nothing odd about this sfz file. Any ideas as to what I'm doing wrong ?

 
It's been a loooong time since I used the sfz player, but I'll take a crack at this anyway.
 
Although the Dimension Mini Piano.sfz says 'Version 2', I still think that the sfz player plays by sfz version 1 format rules.  So there's always the possibility of an unrecognized or superceded opcode causing some weirdness.
 
Where are the .wav files located?  There is no default Multisamples or Sample Pool folders in the sfz player (the first two places that an sfz version 2 synth will 'look' for its defined <region>s).  And I don't recall being able to get the 'redirect' opcodes (like default_path=) to work in the sfz player.
 
So, I believe that all of your .wav samples have to be in properly matched subfolders under the SFZ folder.  .sfz file loading works when the sfz player 'knows' where to look for the component samples.

Thanks b rock, you have identified my problem. After some further inverstigation I've found that sfz will play sfz files,
but only those that do not have default_path=...

There are a few folders in DimPro's Multisample folder that have sfz files without this control opcode and these play just fine.

I realize that this plugin is probably worthless, but I'm just slowly going through this enormous synth called Sonar
that I just bought and want to know what's in it, what works and what doesn't.