google sitemap url is not working

Hi,

I have just installed the google sitemap from products feeds in opencart(1.5.5.1).

Also enabled it and got the url as http://punegrocery.in/index.php?route=f ... le_sitemap

but this url is not working....page keeps loading..i have tried adding this url to google webmaster but the there getting error message as "We were unable to read your Sitemap. It may contain an entry we are unable to recognize. Please validate your Sitemap before resubmitting."

Can anyone help me to identify the cause ?