Brother MFC-6490CW Scanner problems

[Linda]

I'm setting up a new machine with 12.04 LTS stable.  I got 
the Brother MFC-6490CW to work as a printer over the network 
but it will not work as a scanner over the network.  I tired 
all of the possible solutions I found on line adding users 
to groups etc but both Xsane and simple scan fail. In 
frustration I removed the network scanner with brscan3config 
and tried plugging it in with a usb cord. If I do this Xsane 
gives me a  Failed to start scanner:Invalid argument message 
but if you select the scan button again it works. Simple 
scan gives Failed to scan, unable to start scan message. 
Does anyone have any ideas? I could live with having it 
plugged in as a usb scanner but would like to get it working 
without the error message.
                                    Thanks
                                     Linda