FB.ui throwing error

Question

FB.ui({
        method: 'apprequests',
        title: 'Swag with the Swedes',
    message: 'Win 2 tickets to Swedish House Mafia'
}, requestCallback);

I have the code above which throws Uncaught TypeError: Cannot call method 'postMessage' of null

I've searched everywhere for this but no solution. Anyone has any idea of what's wrong?

Thanks

Answer 1

I found the issue.

The following div had to be in the body:

<div id="fb-root"></div>