Can't set up networked users?

Hello,

I'm trying to make it so that my students have the ability to log onto our iMacs (all running Lion) through our Mac Mini Server (also Lion). I recently had to go through drastic changes in order to simply create a directory administrator, in hopes that this would solve the problem, yet it still persists.

The active directory isn't binded onto the server yet. When I try to bind the my Active Directory with the Mac Mini, I get the following popup after logging in as the Directory Admin:

I am honestly at a loss no; I have no clue what to do anymore. Please help!