Make sure the port is disabled for login, then try catting data directly to the printer:
cat /etc/inittab > /dev/ttyx##
Where x## represents the acutall tty device name.
If data prints, you will need look into the spooler configuration. If the data does not print, you should contact Digi Technical Support for further troubleshooting:
http://www.digi.com/support/eservice/eservicelogin.jsp
1 (952) 912-3456