check_printer UNKNOWN - Internal error

I have problem with printers (Ricoh Aficio MP C2800) status monitoring with plugin check_printer after Debian 5 -> 6 upgrade.

./check_printer 192.168.1.8 public alerts UNKNOWN - Internal error

but toners monitoring is fine:

./check_printer 192.168.1.8 public toner 1 OK - Černý toner

HP printers are fine even with status monitoring…