title: Treeview selected node value is null
body: <p>Hello stackoverflow users hope you can help me.</p>
  
  <p>I have populated a treeview control with some data from my database. 
  and it works just fine alle the nodes a created but now i need a category id stored in the node. here is a short description of how I make the nodes.</p>
  
  <pre><code>        TreeNodeCollection nodes = new TreeNodeCollection();
          TreeNode tn = new TreeNode();
          tn.Text =  "&lt;span onclick='return false;'&gt;"+ c.Category_Name +"&lt;/span&gt;";
          tn.Value = c.Category_Id.ToString();
          nodes.Add(tn);
  </code></pre>
  
  <p>then when i try to get the value out again for the example here where i will delete the node from the database ill need the selected category id.</p>
  
  <pre><code> protected void btnDeleteCategory_Click(object sender, ImageClickEventArgs e)
  {
      TreeView1.Nodes.Remove(TreeView1.SelectedNode);
      string categoryId = TreeView1.SelectedNode.Value;
      // run delete method
  }
  </code></pre>
  
  <p>but now the SelectedNode.Value is emty <strong>" "</strong>. but before when i set the value it vasent. 
  I was thinking it can be something with when it populate the treeview, but cant see where it should be ?</p>