Packet logger mode of snort , PROBLEM!

[pink-hat]

hello
I'm a beginner.

I want to test modes of snort in Kali with vmware.
I don't have any problem with sniffer mode but I have a problem with packet logger.

Actually after I use "-l /var/log/snort" in my code , I receive this message :
"WARNING: No preprocessors configured for policy 0"

and nothing appears in the log, and also it isn't any folder or file for logging!

What's the problem? How can I fix it?

Thanks.