Sitemap warnings

Using Sitemap from vbseo. All of a sudden we're getting these errors when I check google webmaster tools:

All the URLs in your Sitemap have the same priority.
All the URLs in your Sitemap are set to the same priority (not the default priority). Priority indicates the importance of a particular URL relative to other URLs on your site, and doesn't impact your site's performance in search results. If all URLs have the same priority, Google can't tell which are more important.

Why is this happening? We haven't changed any settings in the sitemap thing.

It's merely a warning, not an error. The next version of the sitemap has a fix for this. There's also a patch on the forums if you search for "sitemap priority" you should be able to find it. Otherwise, just hold out for the next version to be released shortly.