Unable to update firmware version of Line 6 Monkey software

Hi all,
I have a Line 6 Monkey software, but am unable to update its firmware version. Following what the error states, I carefully placed a USB MIDI cable in the audio/video interface, but still failed.
My computer is using Mac OS X Lion. How can I determine the error code? (see attached screenshot).

I tried updating it using Windows 7 but again, failed.
Could somebody solve my problem? I have searched a lot of forums regarding this problem.
Thanks a lot.
