undefined function, line 132 of LDAPInterface.inc, bizzare error, since same module version works elsewhere.

I'm getting a very pretty (sarcasm) PHP error stating

Fatal error: Call to undefined function ldap_connect() in /home/duran/www/uwbw/sites/all/modules/ldap_integration/includes/LDAPInterface.inc on line 132

This happens when I try to test the connection as defined in the "CONFIGURE LDAP SERVER" screen.

What's interesting, is.. that this is the exact same code base for the module that I'm using on other DRUPAL installs on this same network, and I'm just trying to set up a new instance of drupal with the same LDAP authentication code.

A few months ago I worked through getting the module to work with Active Directory see this URL for what we did.
http://drupal.org/node/429186

It was patched to DEV, and I was able to use that CVS command to download the source code.
I got that working for AD authentication and group management perfectly.
I just copied that exact same source code over to a new instance and I am getting this error.

The only significant difference I can see, is that we're on a 6.12 drupal for this new site, (I haven't upgraded the old one yet), and that its running on a VM inside of my laptop. This vm can connect to the outside world, so I don't think that its a network issue.

Any thoughts?

Thanks.