Cups reports "/usr/lib/cups/backend/hp failed"

Hello ,
today I just set up an HP_LaserJet_M1005 ,
which was a USB multi-function printer and scanner.
It was unable to print anything , and says ,
"usr/lib/cups/backend/hp failed"
I turned the cups log level to "debug" and saw:
Feb 16 22:24:46 hp[6227]: io/hpmud/musb.c 1108: unable to open hp:/usb/HP_LaserJet_M1005?serial=KJ242KT
Feb 16 22:24:46 hp[6227]: prnt/backend/hp.c 745: ERROR: open device failed stat=12: hp:/usb/HP_LaserJet_M1005?serial=KJ242KT
I checked the device permissions,
$stat /dev/bus/usb/004/002
...
Access: (0664/crw-rw-r--) Uid: ( 0/ root) Gid: ( 118/ scanner)
...
After changing to the a=rw mode I succesfully made it print .
Alternately , changing it to group "lp" may also work , if anyone want a try .
As the device is both printer and scanner ,
assigning it to either group will forbit the other to function .
Should we impletement an ACL that both lp and scanner group own it ?
Thanks .
http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=556406