jQuery表单插件成功回调没有执行

码：

<script type="text/javascript">
    $(document).ready(function() {

      var insertOptions =
        { 
            // other available options: 
            url:       'manage_livestock/insert_livestock',type:      'post',dataType:  'json',clearForm: true,//resetForm: true 

            // $.ajax options can be used here too,for example: 
            timeout:   3000,success: showResponse
        };

        $("#livestock").ajaxForm(insertOptions);
    });  

    function showResponse(responseText,statusText,xhr,$form)
    {
        alert('status: ' + statusText + '\n\nresponseText: \n' + responseText + 
            '\n\nsuccess!'); 
    }
</script>

-丰富