HP 3250 AIO; able to print, unable to scan

Installing HP Deskjet 3520 e-ALL-IN-ONE Series Printer

HP-setup couldn't detect the unit.

Installed printer at settings / printers using plus sign.

Able to print to the unit but can't scan. Simple Scan doesn't find a scanner. Neither does Xsane.

Details follow, including hp-check results.

ran sudo hp-setup to use HP Device Manager for printer set-up

used Wireless connection option in window that popped up. Printer wasn't detected. Message in terminal window:

Searching... (bus=net, timeout=5, ttl=4, search=(None) desc=2, method=mdns)
error: No devices found on bus: net

Backed up and clicked on Advanced Options

Tried manual discovery with the IP address from the Printer's settings / wireless

 No devices found on bus:net

Backed up and tried the other discovery option: search for All-in-one only, search term blank, mDNS discovery method

Searching... (bus=net, timeout=5, ttl=4, search=(None) desc=2, method=mdns)
error: No devices found on bus: net

Installed the printer from System Settings / Printers using the Plus sign

Able to print – but Simple Scan doesn't detect a scanner.

Xsane (0.998) didn't detect a scanner either.

http://localhost:631/printers/? CUPS 1.5.3 Found the printer

▼ Queue Name ▼
Description
Location
Make and Model
Status
HP-Deskjet-3520-series
Bev's Deskjet
Credenza
HP Deskjet 3520 Series, hpcups 3.14.10
Idle

CUPS 1.5.3 at http://localhost:631/admin/ add printer shows

Add Printer
Local Printers:
 LPT #1
 HP Printer (HPLIP)
 HP Fax (HPLIP)
Discovered Network Printers:
 Deskjet 3520 series [AE3AA9] (HP Deskjet 3520 series)
 Deskjet 3520 series [AE3AA9] (HP Deskjet 3520 series)
 Deskjet 3520 e-All-in-One Printer series (HP Deskjet 3520 series)
Other Network Printers:
 Backend Error Handler
 Internet Printing Protocol (ipp14)
 AppSocket/HP JetDirect
 Internet Printing Protocol (ipps)
 Internet Printing Protocol (https)
 LPD/LPR Host or Printer
 Internet Printing Protocol (http)
 Internet Printing Protocol (ipp)
 Windows Printer via SAMBA

Here's output from sudo hp-check -r

---------------
| SYSTEM INFO |
---------------

Basic system information:
Linux ToshibaLaptop 3.2.0-74-generic-pae #109-Ubuntu SMP Tue Dec 9 17:00:00 UTC 2014 i686 i686 i386 GNU/Linux

Distribution:
unknown 0.0

Checking Python version...
OK, version 2.7.3 installed

Checking PyQt 4.x version...
OK, version 4.9.1 installed.

Checking for CUPS...
Status: scheduler is running
Version: 1.5.3
error_log is set to level: warn

Checking for dbus/python-dbus...
dbus daemon is running.
python-dbus version: 1.0.0

------------------------
| RUNTIME DEPENDENCIES |
------------------------

Checking for dependency: CUPS - Common Unix Printing System...
OK, found.

Checking for dependency: GhostScript - PostScript and PDF language interpreter and previewer...
OK, found.

Checking for dependency: PIL - Python Imaging Library (required for commandline scanning with hp-scan)...
OK, found.

Checking for dependency: PolicyKit - Administrative policy framework...
OK, found.

Checking for dependency: PyQt 4 DBus - DBus Support for PyQt4...
OK, found.

Checking for dependency: Python DBus - Python bindings for DBus...
OK, found.

Checking for dependency: Python libnotify - Python bindings for the libnotify Desktop notifications...
OK, found.

Checking for dependency: Python XML libraries...
OK, found.

Checking for dependency: Python 2.3 or greater - Required for fax functionality...
OK, found.

Checking for dependency: Reportlab - PDF library for Python...
OK, found.

Checking for dependency: SANE - Scanning library...
OK, found.

Checking for dependency: scanimage - Shell scanning program...
OK, found.

Checking for dependency: xsane - Graphical scanner frontend for SANE...
OK, found.

----------------------
| HPLIP INSTALLATION |
----------------------

Currently installed HPLIP version...
HPLIP 3.14.10 currently installed in '/usr/share/hplip'.

Current contents of '/etc/hp/hplip.conf' file:
# hplip.conf. Generated from hplip.conf.in by configure.

[hplip]
version=3.14.10

[dirs]
home=/usr/share/hplip
run=/var/run
ppd=/usr/share/ppd/hplip/HP
ppdbase=/usr/share/ppd/hplip
doc=/usr/share/doc/hplip-3.14.10
html=/usr/share/doc/hplip-3.14.10
icon=/usr/share/applications
cupsbackend=/usr/lib/cups/backend
cupsfilter=/usr/lib/cups/filter
drv=/usr/share/cups/drv/hp
bin=/usr/bin

# Following values are determined at configure time and cannot be changed.
[configure]
network-build=yes
libusb01-build=no
pp-build=no
gui-build=yes
scanner-build=yes
fax-build=yes
dbus-build=yes
cups11-build=no
doc-build=yes
shadow-build=no
hpijs-install=no
foomatic-drv-install=no
foomatic-ppd-install=no
foomatic-rip-hplip-install=no
hpcups-install=yes
cups-drv-install=yes
cups-ppd-install=no
internal-tag=3.14.10
restricted-build=no
ui-toolkit=qt4
qt3=no
qt4=yes
policy-kit=no
lite-build=no
udev_sysfs_rules=no
hpcups-only-build=no
hpijs-only-build=no

Current contents of '/var/lib/hp/hplip.state' file:
# hplip.state - HPLIP runtime persistent variables.

[plugin]
installed=0
eula=0

Current contents of '~/.hplip/hplip.conf' file:
[upgrade]
notify_upgrade = true
last_upgraded_time = 1418946041
pending_upgrade_time = 0
latest_available_version = 3.14.10

[settings]
systray_visible = 0
systray_messages = 0

[last_used]
device_uri = "hp:/net/Deskjet_3520_series?ip=192.168.1.3"
printer_name =
working_dir = .

[commands]
scan = /usr/bin/xsane -V %SANE_URI%

[refresh]
rate = 30
enable = false
type = 1

[polling]
enable = false
interval = 5
device_list =

[fax]
voice_phone =
email_address =

[installation]
date_time = 14-12-21 22:59:21
version = 3.14.10

--------------------------
| DISCOVERED USB DEVICES |
--------------------------

No devices found.

---------------------------------
| INSTALLED CUPS PRINTER QUEUES |
---------------------------------

HP-Deskjet-3520
---------------
Type: Unknown
Device URI: socket://192.168.1.4:9100
PPD: /etc/cups/ppd/HP-Deskjet-3520.ppd
PPD Description: HP Deskjet 3520 Series, hpcups 3.14.10
Printer Ready to print. HP-Deskjet-3520 is idle. enabled since Mon 22 Dec 2014 04:01:22 PM EST
warning: Printer is not HPLIP installed. Printers must use the hp: or hpfax: CUPS backend to function in HPLIP.

Samsung_ML-2150
---------------
Type: Unknown
Device URI: usb://Samsung/ML-2150?serial=2461B1BX200091W.
PPD: /etc/cups/ppd/Samsung_ML-2150.ppd
PPD Description: Samsung ML-2150 - CUPS+Gutenprint v5.2.8-pre1
Printer Unplugged or turned off_ML-2150 disabled since Wed 17 Dec 2014 08:41:40 PM EST -
warning: Printer is not HPLIP installed. Printers must use the hp: or hpfax: CUPS backend to function in HPLIP.

----------------------
| SANE CONFIGURATION |
----------------------

'hpaio' in '/etc/sane.d/dll.conf'...
OK, found. SANE backend 'hpaio' is properly set up.

Checking output of '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).

**** don't know if I should expect scanimage to find a wireless network printer; SANE project doesn't appear to have much to do with wireless.

**** sane-find-scanner is only good for finding SCSI & USB connected scanners – won't help with the present problem ****

---------------------
| PYTHON EXTENSIONS |
---------------------

Checking 'cupsext' CUPS extension...
OK, found.

Checking 'pcardext' Photocard extension...
OK, found.

Checking 'hpmudext' I/O extension...
OK, found.

Checking 'scanext' SANE scanning extension...
OK, found.

---------------
| USER GROUPS |
---------------

root

error: User needs to be member of group 'lp' to enable print, scan & fax.
error: User needs to be member of group 'lpadmin' to manage printers.

**** I am a member of both groups ****
-----------
| SUMMARY |
-----------

error: 2 errors and/or warnings.

Please refer to the installation instructions at:
http://hplip.sourceforge.net/install/index.html

Ran snmpwalk as part of diagnostic effort:

olaf@ToshibaLaptop:~$ snmpwalk -Os -c public -v 1 ip.address.of.printer 1.3.6.1.4.1.11.2.3.9.1.1.7.0
getaddrinfo: ip.address.of.printer No address associated with hostname
snmpwalk: Unknown host (ip.address.of.printer) (Connection timed out)

********** problem with snmp configuration – but couldn't find instructions on web for fixing it.

Printer works with LibreOffice but Xsane does not detect the scanning functionality

CUPS queue not configured properly
Solution:
For network scanning, the "hp:/net/..." URI must be configured in the CUPS queue for auto-discovery by OpenOffice and xsane. You can manually specify the URI with xsane using the following format:
xsane <"hpaio" device uri>
For example:
xsane hpaio:/net/PSC_750?ip=12.25.63.142
(Where the CUPS installed device URI is: hp:/net/PSC_750?ip=12.25.63.142, and the hp: was replaced with hpaio:)

**** my URI is: socket://192.168.1.4:9100 doesn't look anything like the example

All help will be very much appreciated. Helpers automatically go on Santa's Nice list!!