treeview selected node font style does not change

Hi All,

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" />
           ...