This week's book giveaway is in the Mac OS forum. We're giving away four copies of a choice of "Take Control of Upgrading to Yosemite" or "Take Control of Automating Your Mac" and have Joe Kissell on-line! See this thread for details.
You are right. I was supposed to use not newer. I created two files. One with timestamp on August 30 23:59 and other with Sep 01 12:00. Now I was trying to delete files using between these two file (newer and !newer). Problem is it was also fetching files from sub directories. I don't want to delete files from sub directories.