Use the following link when adding your gadget
This Gadget uses the ShareThis service: http://www.sharethis.com/. We are not affiliated with the ShareThis organization.
This Google Gadget lets the webmaster choose from several types of buttons.
"ShareThis UserID" (Leave the default value if you are not registered with ShareThis)
If you want to track your clicks
"Your Page URL" field needs the URL value for the page that holds the gadget.
Tip: For best results; put in the User URL not the Admin URL
Don't use... https://sites.google.com/...
http://sharethis.com and all of the social media sites like Facebook, Twitter and Google +.
For best results make sure you put some text in your Site "Title" field. Some buttons like Facebook for example scrape your screen to determine its title. Some buttons use the 'Title' field in this Gadget.
More Examples Below