Mcrypt is installed, but error implies it's not.

My issue comes AFTER successfully doing all those things mentioned in the article. My phpinfo() already indicates that mcrypt is enabled and that extension_dir is set to the extension folder of the version of php I'm running. For MAMP, miine is:

/Applications/MAMP/bin/php/php5.5.18/lib/php/extensions/no-debug-non-zts-20121212

Apache, PHP and Mcrypt appear to be installed correctly. The issue occurs when Codeigniter runs the Encryption Class. The constructor for CI_Encrypt "determines whether the mcrypt library exists" with this call:      function_exists('mcrypt_encrypt').

It's that call that fails, and so reports "The Encrypt library requires the Mcrypt extension."