Are you sure about this? I just installed this a few days ago...at first I installed v3 but then I got that error too--then I disabled v3, enabled v2 and regenerated a new key and now it works on my site.
To the developer,
Thank you for a wonderful application! My members love it! Does it cost money for a Bing API though? BING look more fluid in its map from what I've seen.
Ryan