Apache + PHP : Exec format error

[Thomas Linton]

I can't get the package WebCalendar-1.0.0 to work; I always get following
error in /var/log/httpd-error.log

(8)Exec format error: exec of
'/usr/local/www/data-dist/WebCalendar/index.php'

If I put #!/usr/local/bin/php at the beginning of the index.php it works,
however I would like to use the apache module php4_module instead of php as
CGI.

I'm running 5.4-STABLE with the pkg apache-2.0.54_4 and php4-4.4.0 (Apache
Module and CLI).
The httpd.conf includes the line "LoadModule php4_module
libexec/apache2/libphp4.so".

Any ideas?