Only a blank screen

Hello, I've read the FAQ, the manuals of php and apache but doesn't find anything. Here is my problem : I've installed suse 7.2 with apache 1.3.19-48, php 4.0.4 and mysql 3.23.37-8. The file http.conf contains the lines loadmodule and addmodule for php and the lines with addtype application/... When I connect with Konqueror to localhost It display the index.html file wich say apache configured with php, ssl and perl. But when I try to open a file like trial.php3 it displays a blank page. If I would see the source code I can find my php code. More strange, when I made a .php3 file containing html text, the html text appears in konqueror but not in netscape!?! Konqueror could open files like .php3 or .php4 but not .php. Apparently my apache server is well configured so I don't understand where is the problem