starting snort in IDS mode

["Plantier, Spencer" <spencer.plantier () stratech com>]

I have snort up and running. If I do a snort -v it works fine. When I do

snort -d -h 172.30.16.0/22 -l /var/log/snort -c
/var/tmp/snort-2.3.0/etc/snort.conf I get the following. I am new at
unix and any help would be appreciated. 

Thanks. 

# cd ..
# snort -d -h 172.30.16.0/22 -l /var/log/snort -c
/var/tmp/snort-2.3.0/etc/snort.conf
Running in IDS mode
Log directory = /var/log/snort

Initializing Network Interface hme0

        --== Initializing Snort ==--
Initializing Output Plugins!
Decoding Ethernet on interface hme0
Initializing Preprocessors!
Initializing Plug-ins!
Parsing Rules file /var/tmp/snort-2.3.0/etc/snort.conf

+++++++++++++++++++++++++++++++++++++++++++++++++++
Initializing rule chains...
ERROR:  unknown preprocessor "flow"
Fatal Error, Quitting..

Spencer Plantier
System Network Administrator
 
301 Gregson Dr
Cary, NC  27511
Office 919-379-8513
Cell    919-272-8833
spencer.plantier () stratech com