Mopidy Discourse

Mopidy-iris can´t read pendrive

i can´t browse my pendrive and read playlist
my mopidy.conf
[local]
enabled = true
media_dir = /srv/music
#medi_dir= /media/usb
scan_timeout = 1000
scan_flush_threshold = 100
scan_follow_symlinks = false
included_file_extensions =
excluded_file_extensions =