chown ..opperation not permitted

Hi all, My config is Apache 1.3 with PhP4 loaded as a module. I have a script which makes a directory. This directory is owned by nobody.nobody because that is what apache runs as. But, I want this directory to be owned by a differrent user. So, After making the directory i use the php command chown to change the directory ownership. Now, I get an error saying opperation not permitted. I figured this is because of some security problems... So i try dropping in to the shell using teh backtick operator and by also setting up sudo to give access to the chown command to user nobody....this does not work from my php script BUT, it does work fine if i enter it on a shell line... There must be a simple way that I can implement the chown function in php? Any ideas??? John