ASP.NET

public class TreeNodeWithInfo : TreeNode
{.....
}

TreeNodeWithInfo tnGroup = new TreeNodeWithInfo("sdkh", 1);
       TreeView1.Nodes.Add(tnGroup);
      ...

protected void Run_Click(object sender, EventArgs e)
    {
    ...
    ManageTree((TreeNodeWithInfo) TreeView1.Nodes[0]);
     ...
     }
i get a invalid cast exception . The TreeView1.Nodes[0] still has the right information (the one correspongind to the base class , the TreeNode ) but it seems that it's not an instance of TreeNodeWithInfo anymore ..
if i do this in  Run_Click 
<pre>  Response.Write(TreeView1.Nodes[0] is  TreeNodeWithInfo);