WebRTC ICE not working

I'm developing a site which uses WebRTC(Video Calls).
When running site with Firefox "pc.onicecandidate" never launches.
On Chrome this works.
I am using Firefox Aurora and Firefox Nighly with testing.

Part of my code:

pc = new mozRTCPeerConnection({ "iceServers": [{ "url": "stun:" }], optional: [{ 'DataChannels': true }] });

pc.createoffer = offer;
pc.onaddstream = onaddstream;
navigator.mozGetUserMedia({ video: true, audio: true }, function (stream){
    myvideo.mozSrcObject = stream;;
pc.onicecandidate = onice;
function onice (ice){
alert('Got ICE: ' + ice.candidate.candidate);