I have created and uploaded my sitemap to webmaster tools for several different websites but Google keeps showing error codes as below:
X General HTTP error: 404 not found
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.
X Unsupported file format
Your Sitemap does not appear to be in a supported format. Please ensure it meets our Sitemap guidelines and resubmit.
Problem detected on: May 28, 2011
Please advise of a solution..