Site Map issues in Google Webmaster

Hi

I keep getting this issue….

# Type Issue Description Issues count Example Line Detected
1

Errors
Error
We encountered an error while trying to access your Sitemap. Please ensure your Sitemap follows our guidelines and can be accessed at the location you provided and then resubmit.
3
General HTTP error: 404 not found
Sitemap: http://www.andrepaul-photography.com/post-sitemap.xml
HTTP Error: 404
–
Nov 23, 2012
General HTTP error: 404 not found
Sitemap: http://www.andrepaul-photography.com/post_tag-sitemap.xml
HTTP Error: 404
–
Nov 22, 2012
General HTTP error: 404 not found
Sitemap: http://www.andrepaul-photography.com/page-sitemap.xml
HTTP Error: 404
–
Nov 22, 2012
1-1 of 1

http://wordpress.org/extend/plugins/wordpress-seo/