Bug with CUPS and Samsung ML-2550?

[Dave Page]

Using Debian 4.0 with kernel 2.6.18 and CUPS 1.2.7, I try to set up my USB Samsung ML-2550 mono duplex laser printer through the CUPS web interface.

I'm starting from scratch here and deleting any printer config I may previously have had, to document my steps.

I click "Add Printer", give it the name "Samsung", a location and description. For the device, I select the USB device "Samsung ML-2550 USB #1 (Samsung ML-2550" from the drop-down list. For the driver, I provide the recommended Postscript PPD which I downloaded from http://www.linuxprinting.org/show_printer.cgi?recnum=Samsung-ML-2550

I can then look at http://localhost:631/printers/Samsung which shows me:

Samsung
Description: Samsung ML-2550 Mono Duplex Laser
 Location: Next to Tandoor
 Make and Model: Samsung ML-2550 Foomatic/Postscript (recommended)
 Printer State: idle, accepting jobs, published.
 Device URI: usb://Samsung/ML-2550

So far, so good. I go to "Set Printer Options", and set the paper size to A4 and the error policy to "abort-job". I then click "Print Test Page", it gives the job ID "Samsung-13". Now, http://localhost:631/printers/Samsung shows:

Samsung "Printer not connected; will retry in 30 seconds..."
Description: Samsung ML-2550 Mono Duplex Laser
 Location: Next to Tandoor
 Make and Model: Samsung ML-2550 Foomatic/Postscript (recommended)
 Printer State: processing, accepting jobs, published.
 Device URI: usb://Samsung/ML-2550

with the test page job listed at the bottom:

ID           Name        User   Size  Pages     State
Samsung-13   Test Page   root   18k   Unknown   processing since Wed Apr 25 19:47:02 2007

I'm running cupsd in debug mode, but there's nothing in /var/log/cups/error_log which looks useful, just debug information for the web API. In access_log, the relevant lines seem to be:
localhost - root [25/Apr/2007:19:47:02 +0100] "GET /printers/Samsung?op=print-test-page HTTP/1.1" 200 0 - -
localhost - - [25/Apr/2007:19:47:02 +0100] "POST /printers/Samsung HTTP/1.1" 200 18600 Print-Job successful-ok
localhost - root [25/Apr/2007:19:47:02 +0100] "GET /printers/Samsung?op=print-test-page HTTP/1.1" 200 3449 - -
localhost - root [25/Apr/2007:19:47:05 +0100] "GET /printers/Samsung HTTP/1.1" 200 0 - -

/etc/cups/printers.conf:

# Printer configuration file for CUPS v1.2.7
# Written by cupsd on 2007-04-25 19:46
<Printer Samsung>
Info Samsung ML-2550 Mono Duplex Laser
Location Next to Tandoor
DeviceURI usb://Samsung/ML-2550
State Idle
StateTime 1177526575
Accepting Yes
Shared Yes
JobSheets none none
QuotaPeriod 0
PageLimit 0
KLimit 0
OpPolicy default
ErrorPolicy abort-job
</Printer>

cat /etc/cups/cupsd.conf|grep -v ^#|grep [:alnum:]:

Classification none
DefaultCharset UTF-8
DefaultLanguage en
Printcap /var/run/cups/printcap
PrintcapFormat BSD
RemoteRoot remroot
SystemGroup lpadmin
ServerCertificate /etc/cups/ssl/server.crt
ServerKey /etc/cups/ssl/server.key
<Location />
Encryption IfRequested
Satisfy All
Order allow,deny
Allow localhost
</Location>
<Location /admin>
Encryption Required
Satisfy All
Order allow,deny
Allow localhost
</Location>
<Location /admin/conf>
AuthType Basic
Require user @SYSTEM
Encryption IfRequested
Satisfy All
Order allow,deny
Allow localhost
</Location>
HostnameLookups Off
KeepAlive On
KeepAliveTimeout 60
MaxClients 100
MaxRequestSize 0m
Timeout 300
Listen localhost:631
Listen /var/run/cups/cups.sock
AccessLog /var/log/cups/access_log
ErrorLog /var/log/cups/error_log
PageLog /var/log/cups/page_log
MaxLogSize 1m
LogLevel debug
PreserveJobHistory On
PreserveJobFiles Off
AutoPurgeJobs No
MaxJobs 0
MaxJobsPerPrinter 0
MaxJobsPerUser 0
User lp
Group lpadmin
RIPCache 8m
FilterLimit 0
DataDir /usr/share/cups
DocumentRoot /usr/share/cups/doc-root
RequestRoot /var/spool/cups
ServerBin /usr/lib/cups
ServerRoot /etc/cups
TempDir /var/spool/cups/tmp
Browsing Off
defaultauthtype Basic
<policy default>
<limit Send-Document Send-URI Hold-Job Release-Job Restart-Job Purge-Jobs Set-Job-Attributes Create-Job-Subscripti on Renew-Subscription Cancel-Subscription Get-Notifications Reprocess-Job Cancel-Current-Job Suspend-Current-Job Resume-Job CUPS-Move-Job>
require user @OWNER @SYSTEM
order deny,allow
</limit>
<limit Pause-Printer Resume-Printer Set-Printer-Attributes Enable-Printer Disable-Printer Pause-Printer-After-Current-Job Hold-New-Jobs Release-Held-New-Jobs Deactivate-Printer Activate-Printer Restart-Printer Shutdown-Printer Startup-Printer Promote-Job Schedule-Job-After CUPS-Add-Printer CUPS-Delete-Printer CUPS-Add-Class CUPS-Delete-Class CUPS-Accept-Jobs CUPS-Reject-Jobs CUPS-Set-Default>
authtype Basic
require user @SYSTEM
order deny,allow
</limit>
<limit Cancel-Job CUPS-Authenticate-Job>
require user @OWNER @SYSTEM
order deny,allow
</limit>
<limit All>
order deny,allow
</limit>
</policy>

I can print plain text to the printer with "cat file > /dev/usb/lp0", so it's definitely (a) connected and (b) talking to the kernel.