我写的如下，但是好象没有这个方法window.TreeView3.ExpandAll()，请大家帮忙，应该怎么写
<body leftMargin="0" topMargin="0" marginwidth="0" marginheight="0">
<table cellSpacing="0" cellPadding="0" width="100%" border="0">
<tr>
<td align="left" valign="top"><iewc:treeview id="TreeView3" runat="server" Width="100%" SelectExpands="True" SystemImagesPath="/webctrl_client/1_0/treeimages/"></iewc:treeview></td>
<td></td>
</tr>
</table>
<INPUT id="BtnExpandAll" style="DISPLAY: none" onclick="expandall();" type="button" value="ExpandAll">
</FORM>
<SCRIPT language="javascript">
//*********************
//全部展开TreeView
//*********************
function expandall()
{
window.TreeView3.ExpandAll();
}
//*********************
//全部收缩TreeView
//*********************
function collapseall()
{
window.TreeView3.CollapseAll();
}
</SCRIPT>
</body>
</HTML>
