Xsane open to failed device

i am using opensuse 11 version32 bit and i want to connect Musteck bearpaw 2448 scanner,
i have edit the file vi /etc/sane.d/gt68xx.con file and put the firmware using A2Nfw.usb driver,

firmware /usr/share/sane/gt68xx/A2Nfw.usb

when i use this command " scanimage -L" it will display the scanner but when i use the application xsane, the error occur

failed to open device “gt68xx” libusb 0002:0002 invalid argument :frowning:

can you help me how i will solve the problem.