SiteMapPath 不显示子节点
<?xml version="1.0" encoding="utf-8" ?>
<siteMap xmlns="http://schemas.microsoft.com/AspNet/SiteMap-File-1.0" >
<siteMapNode url="Default.aspx" title="站点地图" description="站点地图描述">
<siteMapNode url="" title="1" description="1"></siteMapNode>
<siteMapNode url="" title="2" description="2" />
<siteMapNode url="" title="3" description="3" />
<siteMapNode url="" title="3-0" description="3-0"></siteMapNode>
<siteMapNode url="" title="3-1" description="3-1"></siteMapNode>
<siteMapNode url="" title="3-2" description="3-2"></siteMapNode>
<siteMapNode url="" title="3-3" description="3-3"></siteMapNode>
<siteMapNode url="" title="3-4" description="3-4"></siteMapNode>
<siteMapNode url="" title="4" description="4" />
<siteMapNode url="" title="5" description="5" />
<siteMapNode url="" title="6" description="6" />
<siteMapNode url="" title="7" description="7" />
<siteMapNode url="" title="8" description="8" />
<siteMapNode url="" title="9" description="9" />
</siteMapNode>
</siteMap>
<asp:SiteMapPath ID="SiteMapPath1" runat="server">
</asp:SiteMapPath>
请问为什么不显示底下的啊 1 2 3 ·····啊 只显示 站点地图