Unsupported format with Google

[shoot.the.cat]

Google says the format of the xml generated by "Sitemap Generator" is unsupported format.
What am I doing wong ?
Thanks for the great help I have already had here, and sorry for been a pain.

[XML-Sitemaps Support]

Hello,

please try to resubmit your sitemap.
It looks ok to me - I've just submitted it in my google account and no errors has been found.

[shoot.the.cat]

Odd, I have done nothing, but today when I checked it again, it all seems ok.

Thanks for looking at this for me. I think I have well and truelly worn out my $13 credit with you

[XML-Sitemaps Support]

Ok, great!