Output problem

Hi, After unsuccessful try to install apache2.0.4 with php I went back to apache1.3 and the same php config I had before. Yet for some reason php is not working the way its supposed to. The header function wont do a thing and no syntax errors or warnings are shown . I guess it has to do something with output handling but I didn't find anything on the php.ini file relative to it, in fact I used the old php.ini file (working one). Is there any chance this is an Apache fault ? If not what would you suggest? Thanks. -- georgep