How to tie a javascript function to a treeview with ASP.NET 2

The following code doesn't work:
protected void TreeView1_SelectedNodeChanged(object sender, EventArgs e)
{
string URL = "<script language='Javascript'> showdiv('tabpanel', true);</script>";
Response.Write(URL);

}

My function is loaded in my index.aspx page.

Thank you.

 

LD
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