[Sparkle] dreaded update error....

[Jeremy Matthews]

For some reason, I can't get updates to work, though they did  
before....any ideas?

My appcast xml:

<?xml version="1.0" encoding="utf-8"?>
<rss xmlns:sparkle="http://www.andymatuschak.org/xml-namespaces/ 
sparkle" version="2.0">
   <channel>
     <title>Tomcat Manager Updates</title>
     <link>http://sisuworks.com/tomcatmanagerappcast.xml</link>
     <description>Updates for the &quot;Tomcat Manager&quot; appp by  
SISU Works</description>
     <generator>Feeder 1.4.6 http://reinventedsoftware.com/feeder/</ 
generator>
     <docs>http://blogs.law.harvard.edu/tech/rss</docs>
     <language>en</language>
     <pubDate>Fri, 17 Aug 2007 09:37:46 -0400</pubDate>
     <lastBuildDate>Fri, 17 Aug 2007 09:37:46 -0400</lastBuildDate>
     <item>
       <title>Tomcat Manager 4.2.1 Update</title>
       <link>http://sisuworks.com/Software/Tomcat/Software%20-% 
20Tomcat.html</link>
       <description><![CDATA[<p><b>New Features:</b></p>

<p><b>Interface</b>
<br />- Added additional toolbar icons and removed unnecessary  
buttons</p>

<p><b>Codebase</b>
<br />- Eliminated redundant and unnecessary code</p>]]></description>
       <pubDate>Fri, 17 Aug 2007 09:19:42 -0400</pubDate>
       <enclosure url="http://www.sisuworks.com/files/ 
TomcatManager_4.2.1.zip" length="974067" type="application/zip"  
sparkle:version="4.2.1"/>
       <guid isPermaLink="false">tomcat-manager-421-update</guid>
     </item>
     <item>
       <title>Tomcat Manager 4.2 Release</title>
       <link>http://sisuworks.com/Software/Tomcat/Software%20-% 
20Tomcat.html</link>
       <description><![CDATA[<p><b>New Features:</b></p>

<p><b>Interface</b>
<br />- Separate Panes for each group of application settings
<br />- On/Off Indicators which reflects Tomcat Status on each  
Servlet Instance
<br />- Port Indicators
<br />- jconsole (JVM monitoring) launcher
<br />- Icons that can be used instead of interface buttons (Start,  
Stop, Reload are the only ones working in this release)</p>

<p><b>Settings</b>
<br />- Separate Instance memory management capabilities for minimum,  
maximum, and generational items
<br />- Lots of other stuff coming...</p>]]></description>
       <pubDate>Sun, 05 Aug 2007 15:27:34 -0400</pubDate>
       <enclosure url="http://www.sisuworks.com/files/ 
TomcatManager_4.2.zip" length="962213" type="application/zip"  
sparkle:version="4.2"/>
       <guid isPermaLink="false">local-monitor-13-update</guid>
     </item>
   </channel>
</rss>