Treeview Selected Node Font Style Does Not Change

I have a treeview and I am giving the node style in code behind.

Treeview design is as below:

<asp:TreeView ID="tvIARHierarchies" runat="server" NodeIndent="15" ShowExpandCollapse="true"
ShowLines="True" Width="98%" OnSelectedNodeChanged="tvIARHierarchies_SelectedNodeChanged">
<ParentNodeStyle Font-Bold="False" />
<HoverNodeStyle Font-Underline="True" ForeColor="#6666AA" />
<SelectedNodeStyle Font-Bold="true" BackColor="#6f9dd9" ForeColor="White" />
<RootNodeStyle />
<NodeStyle />
<LeafNodeStyle />
</asp:TreeView>

While populating the tree-view I have a requirement to bind the one particular level with a different colour. So, I am binding it as below

foreach (DataRow row in dr.GetChildRows("rsParentChild"))
{
TreeNode cChild;
if (row["NAME"].ToString() != "")
{
if (row["Level"].ToString().Trim() == "4")
{
string strColor = "DarkOrange";
string fname = "<font id=" + row["NAME"].ToString() + " color ='" + strColor + "'>" + row["NAME"].ToString() + "</font>";
cChild = new TreeNode(fname, row["ID"].ToString());
}
}

Now when the tree view loads, the required level 4 nodes are populated in DarkOrange. But, when any node is selected the backcolour changes as #6f9dd9 as per the style specified in the markup. But the fore-colour does not change.