Prototype+flickrajax请求不适用于Firefox

http://api.flickr.com/services/rest/?method=flickr.photosets.getList&api_key=10cb3dccaa050efebdc01540c1d4d227&user_id=51390557@N07&format=json

如果你运行到任何一个浏览器,你会得到一个flickr功能,是确定的,但我试图获得与Ajax的原型我做了类似的事情

    new Ajax.Request('http://api.flickr.com/services/rest/?method=flickr.photosets.getList&api_key=10cb3dccaa050efebdc01540c1d4d227&user_id=51390557@N07&format=json',
  {
    method:'get',
    onSuccess: function(transport){
        debugger;
      var response = transport.responseText || "no response text";
      alert("Success! \n\n" + response);
    },
    onFailure: function(){ alert('Something went wrong...') }
  });

它在IE中运行良好,但在Firefox中,我不知道为什么我会在responseText中输入一个空白字符串“”。有人知道我做错了什么吗?