Using Burb Suite on Facebook

I am trying to use burb to find some bugs in facebook but the problem that whenever i visit facebook the interceptor doesn't stop the connections with facebook and doesn't show me any data I tried all the ways but this doesn't work on twitter or facebook while the same way i am using works with other sites like Stack Overflow I use the simple way which is setting the default proxy to my browser which is Mozille firefox the newest version Please answer me fast cause it's argent