Problem with Feed Validation CHANNEL

I cannot track down the source of a feed validation error. Let’s start with the Info. WordPress Version 2.3.1, Podpress Version 8.6, although it still states it is 8.5 in the plugin area. All plugins are disabled except podpress. Apache Version 1.3.39 (Unix), PHP Version 5.1.6, My SQL Version 5.0.37-standard-log, Linux OS. Web site is http://www.godsmessageontheweb.net and Feed is at http://www.godsmessageontheweb.net/?feed=podcast

When I validate my feed I get this minor error:
line 3, column 0: Unknown namespace: http://participatoryculture.org/RSSModules/dtv/1.0 which highlights <rss version=”2.0″

The bigger error is if I try to add the podcast to podcast alley I get this:

Critical Errors :

* CRITICAL Empty <channel> tags (code: 1511)

It seems that the error is happening somewhere in these lines of code from the feed-rss2.php

<?php
header('Content-Type: text/xml; charset=' . get_option('blog_charset'), true);
$more = 1;

?>
<?php echo '<?xml version="1.0" encoding="'.get_option('blog_charset').'"?'.'>'; ?>

<!-- generator="wordpress/<?php bloginfo_rss('version') ?>" -->
<rss version="2.0"
xmlns:atom="http://www.w3.org/2005/Atom"
xmlns:content="http://purl.org/rss/1.0/modules/content/"
xmlns:wfw="http://wellformedweb.org/CommentAPI/"
xmlns:dc="http://purl.org/dc/elements/1.1/"
<?php do_action('rss2_ns'); ?>
>
<channel>

I am a newbie with wordpress but have worked with php a little. If I remove this line of code from above
<?php do_action('rss2_ns'); ?> it seems to validate farther. I have been trying to figure out where this line of code pulls the information for itunes and for http://participatoryculture.org/RSSModules/dtv/1.0

Looking forward to hearing from you.

Greg