I am a newbie too, and I've got comparable scanner problems: if I try to scan with Simple Scan, it gives me an error saying it can't connect with the scanner.
My scanner is an Acer ScanPrisa 340U.
sane-find-scanner got me:
found USB scanner (vendor=0x04a5 [Color], product=0x2022 [ FlatbedScanner 13]) at libusb:003:005
# Your USB scanner was (probably) detected. It may or may not be supported by
# SANE. Try scanimage -L and read the backend's manpage.
scanimage -L then gave
No scanners were identified.
lsusb got me:
Bus 003 Device 005: ID 04a5:2022 Acer Peripherals Inc. (now BenQ Corp.) Prisa 320U/340U
I checked here: http://www.sane-project.org/sane-backends.html#SCANNERS
Benq (Acer): 340U USB id 0x04a5/0x2022 Status:Good
But no scanning for me...
I then installed XSane, plugged in the scanner and ran XSane, but I got (approximately; excuse my English translation):
"Couldn't find the scanner 'snapscan:libudb:003:008':
So still no scans...
I then looked around a bit more on the Internet and found the free trial version of VueScan (free trial version means that your scans are watermarked which of course makes the free version unusable).
When I start it up, it recognises my scanner. Then I close VueScan and start up XSane, and... XSane suddenly recognises the scanner too, so I can make my scan. Till I turn off the scanner and put it on again: no recognition by XSane anymore. I first have to run VueScan again to make XSane recognise the scanner.
A very bizarre detour to get my scanner working...
I would be happy if someone could suggest a better way...