My answer to "Installation give me a blank index.php and I can't launch website"

This is my answer to a Question on Support site for LampCMS project

Have you tried launching the phptest.php from the browser? What does the output say?

Try this:
In !config.ini
change
DEBUG = false
to
DEBUG = true

You may want to setup the full path to your log directory
by providing value for
LOG_DIR

Make sure that directory is writable.

Then you should see some log message in the php.log
There may be some clues about the error in the log.

And of cause make sure that the 'w' directory under the 'www' is writable.