Searching Active Directory with .NET (Visual Studio 2005)

First of all...great work. I had been searching for a couple of days for exactly what your screencast showed. I am having some problems though.

Instead of the common name, I would like to display the users logon name. I have been messing around, I got a look at the target's AD schema, and have found some promising attributes to plug in. However, If I try to use and attribute that is not "mandatory" I get a "ArgumentOutOfRangeException"

Here is my code (almost exact to yours)
DirectoryEntry adDirecEntry = new DirectoryEntry();

            DirectorySearcher adDirecSearch = new DirectorySearcher(adDirecEntry);

            //set the search scope
            adDirecSearch.SearchScope = SearchScope.Subtree;

            //Set the filter. For this example we will be looking at all users
            adDirecSearch.Filter = "(ObjectClass=user)";

            //Execute the search and iterate through the result
            //Write results to lboAD for display
           
            foreach (SearchResult adObject in adDirecSearch.FindAll())
            {
                lboAD.Items.Add(adObject.Properties["uid"][0]);
                lboAD.Items.Add(adObject.Path);
            }

It is at "lboAD.Items.Add(adObject.Properties["uid"][0]);" that I get the exception. At first I thought it was maybe something else, I dunno what....but it will only display results when I use a mandatory attribute, no matter the ObjectClass.

Is it something to do with my target's AD schema? Is it something I am doing wrong?

Thanks, and again, great work!!