Google Analytics

Hello,
GA seems not to be working on zoho?
What is META Tag in
Manage > Settings > SEO > Google Analytics & Webmaster Tools
?
Is it mandatory?
If not, when I put my tracker ID from GA ("UA–31913382–1")
in
Manage > Settings > SEO > Google Analytics & Webmaster Tools
Zoho sites says
"Google Analytics Tracking ID is invalid."
Why?
Thanks for your help and products!
Damien from facilojob
facilo (at) facilojob.com