couldn't migrate to php4 - have no idea why

I have a perfectly running php3-mysql-apache-linux system. I want to upgrade
to php4. Cause I want the current system continue untill I am sure that the
new one runs fine, I tried to install apache-php4 in a new
directory. I used the instructions at  http://www.linuxguruz.org/z.php?id=31
except that I didn't try to install mysql again and I didn't use
/usr/local/apache as the directory. Apache didn't start. After reading both
php.ini and httpd.conf line by line I managed to get "./apachectl restart:
httpd restarted" from the command prompt. Lucky right? Nope...

Since I changed all the :80's in httpd.conf to :8090 my dear new server was
waiting at that port. I tried http://myoldworkingwebaddress:8090 and get
this:

Cannot find the server.
The page cannot be displayed
The page you are looking for is currently unavailable. The Web site might be
experiencing technical difficulties, or you may need to adjust your browser
settings, bla bla....

There was nothing in the newly installed apache directories logs.

Any ideas?

Thanks.
Oguz.