Cannot find the network path to get user Full Name or User Groups under the Active Directory

I need to import the full name of a user in the Active Directory. In an environment where the A.D. and the ISS are in the same server I had no problems.

There I had trouble moving the website to a system where the AD and the ISS are in separate machines, I am unable to get the FullName or any other information that must take from Active Directory.

Authentication (AD) is working because it is always necessary to add login and password to open the site. The problem lies when the page is open and need to extract information from the user.

Part of the code:

                obDirEntry = new DirectoryEntry("WinNT://" + strDomain + "/" + strName, "intranet", "intranet");
                System.DirectoryServices.PropertyCollection coll = obDirEntry.Properties;
                object obVal = coll["FullName"].Value;
                str = obVal.ToString();
                return str;

The variables 'strDomain' and 'strName' are ok, the problem lies in the path ("WinNt://...").

This is the error message:

System.Runtime.InteropServices.COMException (0x80070035): The network path was not found. at System.DirectoryServices.DirectoryEntry.Bind(Boolean throwIfFail) at System.DirectoryServices.DirectoryEntry.Bind() at System.DirectoryServices.DirectoryEntry.get_AdsObject() at System.DirectoryServices.PropertyValueCollection.PopulateList() at System.DirectoryServices.PropertyValueCollection..ctor(DirectoryEntry entry, String propertyName) at System.DirectoryServices.PropertyCollection.get_Item(String propertyName) at Ipt.Service.UsuarioService.NomeCompleto(String strLogin)

fullcode:

 public string FullName(string strLogin)
        {
            string str = "";

            int idx = strLogin.IndexOf('\\');
            if (idx == -1)
            {
                idx = strLogin.IndexOf('@');
            }

            string strDomain;
            string strName;

            if (idx != -1)
            {
                strDomain = strLogin.Substring(0, idx);
                strName = strLogin.Substring(idx + 1);
            }
            else
            {
                strDomain = Environment.MachineName;
                strName = strLogin;
            }

            DirectoryEntry obDirEntry = null;
            try
            {
                obDirEntry = new DirectoryEntry("WinNT://" + strDomain + "/" + strName, "intranet", "intranet");
                System.DirectoryServices.PropertyCollection coll = obDirEntry.Properties;
                object obVal = coll["FullName"].Value;
                str = obVal.ToString();
                return str;
            }
            catch (Exception ex)
            {
                str = "";
                return "Erro fullname: " + ex + " --- STRDOMAIN: " + strDomain + "--- STRNAME: " + strName;
            }
        }