What do I need to configure if PHP Pear is working from the command line but not my browser?

My script is dying at

require_once "Mail.php"

I have configured php.ini correctly. It runs from the command line but the exact same script dies in my browser. I'm guessing it's somethi开发者_如何学编程ng simple but I can't quite work out what. Running Centos 5

Edit:

Fatal error: require_once() [function.require]: Failed opening required 'Mail.php' (include_path='.:/usr/share/pear:/local/PEAR/')

which is strange

under /usr/share/pear

I have

-rw-r--r-- 1 root root 8934 Jul 20 2007 Mail.php

PHP has two different .ini files, one for the server module and one for the cli. They must have the same configuration options. Maybe you are missing the pear path in the server module!