after several try-n-errors, I am able to load files from a usb drive ( old and new - even from a usb sd card reader )
the problem that I found is that some usb drives have 2 partitions ( 1 no visible )
linux samplerbox mount the first particion on /media = usually first partition does not have the samples
reformatio the drive ( mac os ) did nothing to remove the ghost partiton.
my solution was to use a digital camara / video camara and format the sd card
and viola .
hope this helps