I have a autocomplete form via url

$(document).ready(function() {
 $("#location").autocomplete({"source":"result.php"});
});

The return json looks like this

1. {"identifier":"name","items":[{"id":"5","name":"New York"}]}

The problem I've got is that I don't see any results in the autocomlete form.
I think I have to match the fields. But how do I do that ?

Thanks