problem Unknown default authorization type Negotiate

[Matthias Ehrig]

hi,

we use cups-1.3.10 under a redhat distribution (scientific linux 5.3).
If I set "DefaultAuthType Negotiate" in my cupsd.conf, then cupsd crashes withe the message

cupsd: Unable to read configuration file '/etc/cups/cupsd.conf' - exiting!cupsd: Child exited with status 1!

and in the cups error_log is the last line (also with debug2):

W [07/May/2009:12:54:59 +0200] Unknown default authorization type Negotiate on line 15.

what could be the reason for this and what are the prerequisites for using authorization type Negotiate ?

thanks for help     Matthias