How much to get my Google site map working properly?

This is what I am getting.

Unsupported file format Your Sitemap does not appear to be in a supported format. Please ensure it meets our Sitemap guidelines and resubmit.

I can give you my log in information if need be.

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what are you using to create it? are you uploading the xml file to root and then linking to it?

Witrh the upgrades issues or what not, I don't have access to the root files.

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