Populating a TreeView using entity framework 4

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C#3.0

C#

entity-framework

I am very new to Entity Framework 4 and i tried populating a TreeView as shown in the figure. But i am getting errors. My lines of code is given.

TreeView

23-June-2013
|--Jaan
|--Prity
24-June-2013
|--Rahul
|--Rajiv

 private void PopulateTreeView()
    {
using (var context = new DiagnosoftContext())
        {
            var q = (from i in context.Patients
                     group i by i.Date into grpDate
                     select grpDate);


foreach (var item in q)
            {
                TreeNode nodes = new TreeNode(q.ToString());    //Create root node first
                TreeNode tn = item as TreeNode;

                var childNodes = q;         //Next sub-query to be write
                foreach (var child in childNodes)        //Adding child nodes to root node if it have any
                {
                    TreeNode childNode = new TreeNode(q.ToString());
                    nodes.Nodes.Add(childNode);
                }
                treePatient.Nodes.Add(nodes);           //At the last add the root node with child nodes to treeview

            }

        }
}


public class Patient
{      
        public int PatientId { get; set; }
        public int RegisteredNo { get; set; }
        public DateTime Date { get; set; }
        public string PatientName { get; set; }
        public int Age { get; set; }
        public int Sex { get; set; }
}

Please help me. Thank you in advance.