mod_rewrite causes apache to crash with Rewritemap prg directive

Question

Apache configuration:

RewriteEngine on
RewriteLock /var/www/lib/rewrite.lock
RewriteMap sessionValid prg:/var/www/lib/allow.php

I fixed the obvious of setting the file executable, but now it is giving this:

[Fri Feb 12 01:55:31 2010] [error] (2)No such file or directory: 
exec of '/var/www/lib/allow.php' failed

But the file clearly exists.

Answer 1

...Forgot to make allow.php executable for the apache user.