In my log file i am having the x-category field with following values

server,vhost,application,session,stream,rtsp

But i need only session and stream
I have tried this in log4j

log4j.appender.serverAccess.layout.Category=session,stream
But am getting the error
log4j:WARN No such property [category] in com.wowza.wms.logging.ECLFPatternLayout.
and server is started.And no changes in the log file.
Please tell me what to do.