U00->
15 Synth->
(List of samples in individual zip folders. example. 02.Synclavier_BellGong)
If
u00 is at the top-level of the USB stick, then that's the problem. The top-level directory should be
px.
If
u00 is already at the proper spot, i.e.,
/px/u00/…, then either try renaming the
u00 to use a lowercase
u, just in case. (I'm not in the studio the check on my synth.)
Another thing to consider: the
.wav files need to be 16-bit linear, 48 kHz WAV files.