I cannot check all the ChildNodes in my ParentNode?

Question

hi,
I ahve create a TreeView Control wiht check boxes:
 
I have created a parent Tree Node as:

 

TreeNode parentNode = new TreeNode("Departments");

 
Then i have added four childNodes

 

for(int i=0; i< 4; i++)
{
   TreeNode childNode = new TreeNode(i.ToString());
   parentNode.Nodes.add(childNode);
}
 
TreeViewControl.Nodes.add(parentNode)

 
Then i need to check all the childsNodes if parentNode is Checked so....

 

 
private void tvDepartments_AfterCheck(object sender, TreeViewEventArgs e)
{
               if (e.Node.Name.ToString() == "parentNode")
                {
                   foreach (TreeNode item in e.Node.Nodes)
                   {
                        item.Checked = true; 
                   } 
                 } 
}

 
The problem is that the control woudlnt go into the if statement... How do i fix this?
TY