I received an email that said one of my pages does not have the ad link so my site will not validate. The problem is that the page mentioned does not exist. I rechecked my site to make sure I did not have an old link and I did not. Why is it picking up on a html page when all of my pages are shtml? Thanks
If the pages are indexed on google, then it'll ask you to validate again - until the page contains the code.
Do a 301 redirect using htaccess to your sitemap page from the page it's asking for and it should validate. If not, it will when Google drops the old URL it has.
Or make a page and add the code just for it, if it's just the one. And 301 it so it's only a temporary fix.