Sharing Problem on Facebook 403 Forbidden Error

[friendlymela]

Hey Friends, I have a problem, when i am trying to share any thread/page on facebook i got this error 403 Forbidden. because of this i am not sharing threads anymore. please someone help me how i can solve it. everything is working fine on my forum (http://www.friendlymela.com)

https://vborg.vbsupport.ru/external/2015/10/1.png