I dont hnow what the stick you say but
yesterday I mount a 32G stick in a vu+uno with
VTI image. It works 100%
You must go to the PVR key and key twice.
Then you have to make a BOOKMARK
It is not easy. You must use the Channels keys
til you see something like SDA1 XXXXXX
then GREEN key.
NOTE: The USB stick must be formated in windows FAT
After, in the menu, you have to save this settings.
It works 100%
Good luck
NOTE: The USB stick must be formated in windows fat32