Google Webmaster Tool says Sitemap has errors but No errors or warnings found?

[webwit]

I submitted my sitemaps to google.

But when I checked webmaster tools later it had a red X under status like if the sitemap submission failed? But when I click on it the sitemaps all have a green checkmark next to them and it says "No errors or warnings found", what is going on?

[klicker]

That's weird, usually GWT will give you details of the error, such as:

Compression error
Empty Sitemap
Invalid attribute value
Invalid date
Invalid tag value
Invalid URL
Invalid URL: We've detected that a Sitemap you've listed doesn't include the full URL.
Invalid XML: too many tags
Missing XML attribute
Missing XML tag
Nested indexing
Parsing error
Temporary error
Too many Sitemaps
Too many URLs
Unsupported file format
URL not allowed
Paths don't match: We've detected that you submitted your Sitemap using a URL path that doesn't include the www prefix.
Paths don't match: We've detected that you submitted your Sitemap using a URL path that includes the www prefix.
Incorrect namespace
Leading whitespace
A specific HTTP error

(Took this list from google's help page: Sitemap errors - Webmasters/Site owners Help )

In what manner was your sitemap generated?

[webwit]

vBSEO Google/Yahoo Sitemap Generator