have treeview which displays on the screen, pls help me

i have treeview which displays on the screen

for this , i have written coding masterpage. becuse these treeview should come in all pages.

category : button
when you click category it will show treeview record.

+ football
-football1
-football2
+volleyball
.
.
.
.
+stemperball.

these everithing i am binding from sqlserver data base.

in master design page, i creaed content placeholder like follows

<asp:ContentPlaceHolder ID="ContentPlaceHolder2" runat="server">
</asp:ContentPlaceHolder> // this content only is having sports page.



and i have another web form called sports.aspx. in that page i want to show that if you click + it will expand it's child football1,football2...when you click on node(football) from treeview, it will show football images (Note: here using OnSelectedNodeChanged , i will pass the unique id to sports.aspx. so now using football unique id, the sports aspx page will show it's images. similarly for volleyball and etc)

<asp:Content ID="conten1" ContentPlaceHolderID="ContentPlaceHolder2" runat="server" >
{
.//datalist which shows image of football.
.
.
}

till now works fine. the problem is that: when we clikc football node, the images displays, but the treeview get collapsed. the category only shows.

i tried with expand and collapse option. pls help me out.