Do you have a sitemap setup in the content tree using the Google Sitemap XML webpart? Also do you have the site settings configured with this URL? Settings>URLs & SEO>Search engine optimization>Google sitemap UR and Google sitemap path. They should have settings similar to what I have here:
![Image Text](https://kehrendev.tinytake.com/media/2387d8?filename=1450725139896_21-12-2015-01-12-18.png&type=attachment)
The sitemap path is where the sitemap resides in your content tree. The sitemap URL is what you provide to google. For instance, www.yourdomain.com/googlesitemap.xml