URL’s not followed?

I’m having a problem with my sitemap.xml

Webmaster tools is giving me a warning message:

– URLs not followed
When we tested a sample of URLs from your Sitemap, we found that some URLs redirect to other locations. We recommend that your Sitemap contain URLs that point to the final destination (the redirect target) instead of redirecting to another URL.

And then it tells me that these are causing the problem:

HTTP Error:
Problem detected on: 301 (Moved permanently) Help
http://blog.propixelphotography.com/index.php/tag/celebration/
http://blog.propixelphotography.com/index.php/tag/hampton-roads/
http://blog.propixelphotography.com/index.php/tag/studio/
http://blog.propixelphotography.com/index.php/tag/seminar/
Mar 3, 2009

I checked the actual URL from my blog and the links are good. Everything seems to be normal.

What’s causing this? How can I fix it?

Thanks

-H