unhandled exception c# dll

Question

I tring to test a new dll that I've build for c#

private void button1_Click(object sender, EventArgs e)
        {
            String [] first = UserQuery.Get_All_Users();
            //MessageBox.Show(first);
        }

but I get the following error at String [] first = UserQuery.Get_All_Users();

An unhandled exception of type 'System.NullReferenceException' occurred in User_Query.dll

Additional information: Object reference not set to an instance of an object.

I been tring to figure this one out for hours but can't find any null varibles

I post my dll in case the dll is wrong

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.DirectoryServices;

namespace User_Query
{
    public class UserQuery
    {
        public static string[] Get_All_Users()
        {
            string[] names = new string[10];

            var path = string.Format("WinNT://{0},computer", Environment.MachineName);

            using (var computerEntry = new DirectoryEntry(path))
            {
                var userNames = from DirectoryEntry childEntry in computerEntry.Children
                                where childEntry.SchemaClassName == "User"
                                select childEntry.Name;
                byte i = 0;
                foreach (var name in userNames)
                {
                    Console.WriteLine(name);
                    names[i] = name;
                    i++;
                }
                return names;
            }           
        }
    }
}

Answer 1

There is a problem with your. path variable... since there should be \\\\ instead of //

Answer 2

The problem here turned out not to be the code but be VS2010 not loading the dll. This happen because I decided to change the program from using the dll from the debug to the release version but I did not clean the project after doing it and therefore the program was not correctly loading the dll. All that need to be done was clean the project