Social Importer failure – Signature was invalid

Hi GD support team,

I have the issue trying to import data from yelp using the social importer it not working.
I am getting the browser message “signature was invalid”

screen shot “failure” – http://screencast.com/t/T4G6IVoPFT
screen shot “settings” – http://screencast.com/t/rGtID83Q5YBm
screen shot “yelp listing to add” – http://screencast.com/t/45jqo9UbJN

URL to add
Yelp Listing URL

History info:
1. In backend I checked the licence activated correct.
2. I tried same by de-activating most of plugins in use
3. I tried by using an extra sandbox installation

with same not able to use results.

Please help to find out and check, why the social importer is not working any more.

Best regards, Alex