Google site map error

:: i read the googlesite map tutorial and followed all the step but still error
The step i took were following
created a account in google webmaster tools
selected a meta tag option and copied the meta tag and i paste in my refrecer by control panel
verifyed and my forum got verifyed too
after that selected general site map option and submitted >>> Sitemap.xtml and submit that
Aftr submisi0n of it problem started there was an error . . . It got submitd bt when i checkd the status there was an error again i resubmit bt again there was an error please puzzel out with this ErRROR