Comment 10 for bug 135194

Did you check your user's permissions?

There was a bug earlier in beta where the user was not automatically added to the groups "use tape drives", "use scanner" and "send and recieve faxes".

I had the exact same error message and adding those groups to my profile fixed it, the detection part that is. The sane and sane-tools actually allowed my scanner to scan, albeit not always reliably.

Go to: System>Administration>Users & Groups, unlock and enter your password, select your user and click properties, then on the second tab select all groups that haven't been selected. Make sure you relog, and then try to see if your scanner does get detected by the system.

Good luck.