Was able to figure out the issue..
instead of war level log4j.xmls ; i had it ear level
Also there were 2 versions of log4j jars even that caused an exception
I read that we need to have only 1 version
even though strangely the same code works on WAS5.1 with both version of jars but doesnt in WAS6.1
removed the older version and now its working fine
Thanks everyone