I'm assuming this is coming up during the early part of the installation, correct?
Are you installing on a Win2K system? You may need to point us as a different LDAP port. If you're running 2.4.0 or later it should be coming up and asking you to provide an LDAP port (not sure which version you're trying to install). The default port is 389, but AD parks on that in Win2K so you need to move it in Exchange and tell our setup where the new port number is.
Also, be sure you change it on the server we're installing on in the Exchange administrator and remove the "use site defaults for all settings" check box... I've had a couple people stumble on that. The UI is not the most intuative. It lets you change the port and even hit the enable LDAP protocol checkbox, but the site defaults will over ride if you don't also clear that box.
If I'm running down the wrong path here, let me know...
Jeff Lindborg
Unity Product Architect
Active Voice
jlindborg@activevoice.com
http://members.home.net/jlindborg