If you’re using Openinviter, you probably got this error while trying to use the Twitter service:
'Unable to get contacts'
Same thing will happen using the online demo.
This is due to a recent Twitter update forcing SSL on mobile version (The Openinviter plugin is not using the official API methods but a clever interaction with the mobile version of Twitter).
To fix that issue, just open the /OpenInviter/plugins/twitter.plg.php file and change all the http references to https.
Btw, this will also fix the send invitations problem (if you ever succeeded to get contacts).
It should work flawlessly 
And what about Facebook? I get the same error… there is a workaround for facebook too?
Hi, have you tried this patch ?
http://www.thecodedeveloper.com/openinviter-facebook-plugin
yes,and it didnt work at all