Issue with group by clause in linq to sql

var qry1 = from d in department 
         select new {
               deptname = d.deptname,
               ucount   = (from u in users where u.deptid == d.deptid select u).Count()
         };

var qry2 = from u in users group u by u.deptid into grp
    select new { Deptid = grp.Key, UsersCount = grp.Count() };

var qry3 = from u in usrs 
			join d in depts on u.DeptId equals d.DeptId
			group d by d.DeptName into grp
			select new {
				DeptName = grp.Key,
				UsersCount = grp.Count()
				};

void Main()
{

	List<Department> depts = new List<Department>
		{
			new Department(1, "A"),		
			new Department(2, "B"),
			new Department(3, "C")
		};
	
	List<User> usrs = new List<User>
		{
			new User(1), new User(1),
			new User(2), new User(2),
			new User(2), new User(1),
			new User(1), new User(3),
			new User(3), new User(3),
			new User(3), new User(3),
			new User(3), new User(3),
			new User(3), new User(3),
			new User(3)
		};
	
	
	var qry1 = from d in depts 
         select new {
               DeptName = d.DeptName,
               UsersCount   = (from u in usrs where u.DeptId == d.DeptId select u).Count()
         };
		qry1.Dump();
	
	var qry2 = from u in usrs group u by u.DeptId into grp
    			select new { DeptId = grp.Key, UsersCount = grp.Count()};
	qry2.Dump();

	var qry3 = from u in usrs 
				join d in depts on u.DeptId equals d.DeptId
				group d by d.DeptName into grp
				select new {
					DeptName = grp.Key,
					UsersCount = grp.Count()
					};
	qry3.Dump();
	
}

// Define other methods and classes here
class Department
{
	private int did =0;
	private string dna = string.Empty;
	
	public Department(int _did, string _dna)
	{
		did = _did;
		dna = _dna;
	}
	
	public int DeptId
	{
		get{return did;}
		set{did = value;}
	}

	public string DeptName
	{
		get{return dna;}
		set{dna = value;}
	}
}

class User
{
	private int did = 0;
	
	public User(int _did)
	{
		did = _did;
	}
	
	public int DeptId
	{
		get{return did;}
		set{did = value;}
	}
}

DeptName UsersCount
A        4
B        3
C        10

DeptId UsersCount
1      4
2      3
3      10

DeptName UsersCount
A        4
B        3
C        10