nginx - ubuntu: Installed php-mcrypt but it doesn't show up in phpinfo()

A web app I'm trying to install on my ubuntu 10.04 LTS requires mcrypt, and is generating this error: Fatal error: Call to undefined function mcrypt_module_open(). I know this is the same question as this one: Installed php-mcrypt but it doesn't show up in phpinfo(), but I tried several things, none of which worked, and have additional questions. I would comment on the original thread but don't have enough reputation to do so; forgive me for the duplicate question.

My versions of php and mcrypt are (both installed via apt-get):

php: 5.3.2-1ubuntu4.10
mcrypt: 5.3.2-0ubuntu

Doing a php -m shows that the mcrypt module is installed. I installed mcrypt and php5-mcrypt via apt-get.

Also, I'm using nginx as my web server. I have tried reinstalling mcrypt and restarting nginx, but still can't get mcrypt to show up on phpinfo() and calls to mcrypt are still broken.

Here is some more info:

$ php -i | grep "mcrypt"
/etc/php5/cli/conf.d/mcrypt.ini,
mcrypt

mcrypt support => enabled
mcrypt.algorithms_dir => no value => no value
mcrypt.modes_dir => no value => no value

I also checked that mcrypt is on in /etc/php5/cli/conf.d/mcrypt.ini and /etc/php5/cgi/conf.d/mcrypt.ini.

Lastly, I'm using fastCGI with nginx. I googled around and saw suggestions to restart php5-fpm. I couldn't find php5-fpm in apt-get, I'm not sure if I still need php5-fpm since I already have fastCGI.

Is there anything else I'm missing?