[CentOS] Problems getting scanner to work from xsane (from Gnome Menu or GIMP)

We have a networked HP OfficeJet All-In-One.  I have the scanner working
with the CentOS 5.3, except xsane is ignoring SANE_DEFAULT_DEVICE. 
scanimage does however take this environment variable just fine:

server1.wendellfreelibrary.org% scanimage -L

No scanners were identified. If you were expecting something different,
check that the scanner is plugged in, turned on and detected by the
sane-find-scanner tool (if appropriate). Please read the documentation
which came with this software (README, FAQ, manpages).
default device is `hpaio:/net/Officejet_Pro_L7700?ip=192.168.1.253'
server1.wendellfreelibrary.org% scanimage -T
scanimage: scanning image of size 638x1125 pixels at 24 bits/pixel
scanimage: acquiring RGB frame, 8 bits/sample
scanimage: reading one scanline, 1914 bytes...  PASS
scanimage: reading one byte...          PASS
scanimage: stepped read, 2 bytes...     PASS
scanimage: stepped read, 4 bytes...     PASS
scanimage: stepped read, 8 bytes...     PASS
scanimage: stepped read, 16 bytes...    PASS
scanimage: stepped read, 32 bytes...    PASS
scanimage: stepped read, 64 bytes...    PASS
scanimage: stepped read, 128 bytes...   PASS
scanimage: stepped read, 256 bytes...   PASS
scanimage: stepped read, 512 bytes...   PASS
scanimage: stepped read, 1024 bytes...  PASS
scanimage: stepped read, 2048 bytes...  PASS
scanimage: stepped read, 2047 bytes...  PASS
scanimage: stepped read, 1023 bytes...  PASS
scanimage: stepped read, 511 bytes...   PASS
scanimage: stepped read, 255 bytes...   PASS
scanimage: stepped read, 127 bytes...   PASS
scanimage: stepped read, 63 bytes...    PASS
scanimage: stepped read, 31 bytes...    PASS
scanimage: stepped read, 15 bytes...    PASS
scanimage: stepped read, 7 bytes...     PASS
scanimage: stepped read, 3 bytes...     PASS
server1.wendellfreelibrary.org% echo "$SANE_DEFAULT_DEVICE"
hpaio:/net/Officejet_Pro_L7700?ip=192.168.1.253

xsane just pops up a little window "scanning for devices", the "no
devices available".

I believe I have things properly setup with cups:

In /etc/cups/printers.conf:

<Printer Officejet_Color>
Info 
Location Printer Area
#DeviceURI socket://192.168.1.253:9100
DeviceURI hp:/net/Officejet_Pro_L7700?ip=192.168.1.253
State Idle
StateTime 1211313246
Accepting Yes
Shared Yes
JobSheets none none
QuotaPeriod 0
PageLimit 0
KLimit 0
OpPolicy default
ErrorPolicy retry-job
</Printer>


-- 
Robert Heller             -- Get the Deepwoods Software FireFox Toolbar!
Deepwoods Software        -- Linux Installation and Administration
http://www.deepsoft.com/  -- Web Hosting, with CGI and Database
heller at deepsoft.com       -- Contract Programming: C/C++, Tcl/Tk