Horizontal menu doesn't "dropdown"

[Randy Smith]

Hi All,
My menu control doesn't "dropdown". The "Home" menu item doesn't appear,
nor does the "Jobs" item. And, the 2nd group (Labor and Materials) in
web.sitemap doesn't appear at all. The Here's what web.sitemap looks like:
<?xml version="1.0" encoding="utf-8" ?>

<siteMap xmlns="http://schemas.microsoft.com/AspNet/SiteMap-File-1.0" >

<siteMapNode title="Home" url="ShowAllJobs.aspx">

<siteMapNode title="Jobs" url="">

<siteMapNode title="Add New Job" url="AddNewJob.aspx" />

<siteMapNode title="Show Job Details"
url="showJobDetails.aspx" />

<siteMapNode title="Show Unaccepted Jobs"
url="showUnacceptedJobs.aspx" />

<siteMapNode title="Get Job Step" url="getJobStepData.aspx"
/>

<siteMapNode title="Show Pending Jobs"
url="ShowPendingJobs.aspx" />

</siteMapNode>

<siteMapNode title="Labor and Materials" url="LaborMaterials.aspx" >

<siteMapNode title="Add Labor Rate" url="addNewLaborRate.aspx"
/>

<siteMapNode title="Show Labor Rate" url="showLaborRates.aspx"
/>

</siteMapNode>

</siteMapNode>

</siteMap>

Is there some property that I'm missing that allows the dropdown items to
appear?