I just entered the podcast world. I am having trouble with my rss code. This is the error i recieve from itunes when trying to submit the url. Error Parsing Feed: invalid XML:Error line 64:XML documents must start and end within the same entity

Question

<?xml version="1.0"?>
<rss xmlns:content="http://purl.org/rss/1.0/modules/content/"
xmlns:itunes="http://www.itunes.com/DTDs/Podcast-1.0.dtd"
Verson="2.0">
<channel>
<title>KPNC Regional Toxcast</title>
<link>http://kpssctoxicology.org/edu.htm</link>
<description>KP Toxcast test podcast</description>
<webMaster>[email protected]</webMaster>
<managingEditor>[email protected]</managingEditor>
<pubDate>Tue, 27 Sep 2011 14:21:32 PST</pubDate>
<category>Science & Medicine</category>
  <image>
   <url>http://kpssctoxicology.org/images/kp tox logo.jpg</url>
   <width>100</width>
   <height>100</height>
   <title>KPNC Regional Toxcast</title>
  </image>
<copyright>Copyright 2011 Kaiser Permanente. All Rights Reserved.</copyright>
<language>en-us</language>
<docs>http://blogs.law.harvard.edu/tech/rss</docs>
<!-- iTunes specific namespace channel elements -->
<itunes:subtitle>The Kaiser Permanente Northern California (KPNC) Regional Toxicology Service                  Podcast</itunes:subtitle>
<itunes:summary>This is the podcast (toxcast) of the KPNC Regional Toxicology Service. Providing                 Kaiser and non-Kaiser physicians with anything toxworthy</itunes:summary>
<itunes:owner>
   <itunes:email>[email protected]</itunes:email>
   <itunes:name>G. Patrick Daubert, MD</itunes:name>
</itunes:owner>
<itunes:author>G. Patrick Daubert, MD</itunes:author>
<itunes:category text="Science & Medicine"></itunes:category>
<itunes:link rel="image" type="video/jpeg" href="http://kpssctoxicology.org/images/kp tox                   logo.jpg">KPNC Toxcast</itunes:link>
<itunes:explicit>no</itunes:explicit>
<item>
   <title>KPNC Regional Toxcast Sample File</title>
   <link>http://kpssctoxicology.org/edu.htm</link>
   <comments>http://kpssctoxicology.org#comments</comments>
   <description>This is the podcast (toxcast) of the KPNC Regional Toxicology Service. Providing                Kaiser and non-Kaiser physicians with anything toxworthy</description>
   <guid isPermalink="false">1808@http://kpssctoxicology.org/Podcast/</guid>
   <pubDate>Tue, 27 Sep 2011 14:21:32 PST</pubDate>
   <category>Science & Medicine</category>
   <author>[email protected]</author>
   <enclosure url="http://kpssctoxicology.org/podcast/kptoxcast_test_092711.mp3" length="367000"                   type="audio/mpeg" />
   <!-- RDF 1.0 specific namespace item attribute -->
   <content:encoded><![CDATA[<p><strong>Show Notes</strong></p>
   <p><a href="KPNC" _mce_href="http://kpssctoxicology.org/">KPNC">http://kpssctoxicology.org/">KPNC Regional Toxicology Service</a> is comprised of               Steve Offerman, MD; Michael Young, MD; Patrick Whitely; and G. Patrick Daubert, MD.               Awesome team!
   <p>Download <a href="KPNC" _mce_href="http://kpssctoxicology.org/podcast/kptoxcast_test_092711.mp3">KPNC"> http://kpssctoxicology.org/podcast/kptoxcast_test_092711.mp3">KPNC Sample               Toxcast</a></p>]]</content:encoded>
   <!-- iTunes specific namespace channel elements -->
   <itunes:author>G. Patrick Daubert, MD</itunes:author>
   <itunes:subtitle>The Kaiser Permanente Northern California (KPNC) Regional Toxicology Service                    Podcast</itunes:subtitle>
   <itunes:summary>This is the podcast (toxcast) of the KPNC Regional Toxicology Service.                   Providing Kaiser and non-Kaiser physicians with anything
                   toxworthy </itunes:summary>
   <itunes:category text="Medicine"></itunes:category>
   <itunes:duration>00:00:18</itunes:duration>
   <itunes:explicit>no</itunes:explicit>
   <itunes:keywords>daubert,toxicology,toxcast</itunes:keywords>
  </item>
</channel>
</rss>

Answer 1

Please when you have a query post the URL of your feed, not its contents.  Is this your feed? -
http://kpssctoxicology.org/Podcast/kptoxcast_test_rss_092711.xml
You have a number of cases of a string of spaces in titles: you also have one in a URL which will render that link invalid.
But what is rendering the whole feed unreadable is your category link:
<category>Science & Medicine</category>
The presence of an ampersand ('&') by itself indicates the start of a code sequence, and in the absence of one, and its closing character, invalidates everything which follows, and thus the entire feed. You must replace the ampersand with the code
&amp;
Additionally, your opening lines should read thus:
<?xml version="1.0" encoding="UTF-8"?>
<rss xmlns:itunes="http://www.itunes.com/dtds/podcast-1.0.dtd" version="2.0">
(with the 'purl.org' line if you like).
If you are going to submit a feed to iTunes you might want to reconsider have 'test' in the filename: apart from the Store having a tendency to reject obvious test podcasts which may not reflect the finished version, you will be stuck with this URL and though you can change the feed URL it's an additional hassle.