This feature is not supported anymore by Digg.com.
Digg.com is a social bookmarking and news site. Users submit stories, then vote on which stories make it to the front page. With this plugin you can add Digg buttons to your posts by just checking a box in the Write tab. Or change one setting and instantly add the button to all of your posts. You and your readers can click the Digg button to add your post to Digg. Once the post has been submitted, the button will show how many Diggs the story has.
Works with b2evolution 1.8 and higher (including 2.x).