无法访问返回对象中的属性

msgBox()

{ \"Addresses\" : 
    \"[{ 
        Building=Megatron Skyscraper,
        BuldingId=1998,
        AccountId=2000,
        Number=007,
        Name=Megatron 
        },{
        Building=StarScream Skyscraper,
        BuldingId=1999,
        AccountId=2001,
        Number=008,
        Name=StarScream
}]\"}

function getReadyStateHandler(req)
{
    // Return an anonymous function that listens to the
    // XMLHttpRequest instance
    return function ()
    {
        // If the request\'s status is \"complete\"
        if (req.readyState == 4)
        {
            // Check that a successful server response was received
            if (req.status == 200)
            {
                msgBox(\"JSON Response recieved...\");
                var addresses = req.responseText.toJSON();
                msgBox(req.responseText.toJSON());
            }
            else
            {
                // An HTTP problem has occurred
                alert(\"HTTP error: \" + req.status);
            }
        }
    }
}

addresses.Address[0].City

addressess.Addresses[0].City