I'm trying to get all domains that are available in the Windows Login dialog (in the Domain dropdown).

I've tried the following code but it only returns the domain I am logged into. Am I missing something?

StringCollection domainList = new StringCollection();
try
{
    DirectoryEntry en = new DirectoryEntry("LDAP://");
    // Search for objectCategory type "Domain"
    DirectorySearcher srch = new DirectorySearcher("objectCategory=Domain");
    SearchResultCollection coll = srch.FindAll();
    // Enumerate over each returned domain.
    foreach (SearchResult rs in coll)
    {
        ResultPropertyCollection resultPropColl = rs.Properties;
        foreach( object domainName in resultPropColl["name"])
        {
            domainList.Add(domainName.ToString());
        }
    }
}
catch (Exception ex)
{
    Trace.Write(ex.Message);
}
return domainList;