Hi Maria,
This sounds like a permissions issue. Can you try to run the application with sudo? If that fixed the problem, and you don't want to have to run as sudo then you can update the udev configuration.
For example, edit or add /etc/udev/rules.d/99-local.rules and add the line:
SUBSYSTEM=="usb", ATTR{idVendor}=="1d5a", MODE="0666"
Please let me know if this fixes your issue or if there is anything else I can help with. Thanks.
-Merrill
libfreespace moderator