$http.JSONP always get status 0

It is a problem about AngularJS maybe, however I cannot login StackOverflow here(gfw result).Is there someone can help me ? thx;

$http({method:'jsonp', url:'http://animelock.com/test.json?callback=JSON_CALLBACK'}).
	alert('GET SUCCESS. '+ ' DATA: '+ data + '  STATUS:'+status);
	alert('GET FAIL. '+ ' DATA: '+ data + '  STATUS:'+status);

and I always get an alert of: GET FAIL DATA:undefined STATUS:0

In chrome’s dev tool, the GET is 304,and the Response is true…
I even find that other situation it return 0 too… I dont’t know why it always go into the ‘error’…

Is it an CORS problem ? but JSOP and GET gets the same problem and return…