求助，Windows Phone 7调用WebService时，报错

private void loginButton_Click(object sender, RoutedEventArgs e)
{
//实例化一个WebService代理对象
Service.Service1SoapClient ssc = new Service.Service1SoapClient();

//user方法调用完之后触发的事件
ssc.userCompleted += new EventHandler<Service.userCompletedEventArgs>(ssc_userCompleted);

ssc.userAsync(userTextBox.Text, pwdTextBox.Text);

}

void ssc_userCompleted(object sender, Service.userCompletedEventArgs e)
{
if (e.Error == null)
{
XElement x = XElement.Load(e.Result.ToString());
}
throw new NotImplementedException();
}


请问为什么会报下面这个错误，求助


“System.InvalidOperationException”类型的未经处理的异常出现在 System.Xml.dll 中。

其他信息: There was an error reflecting type 'WebSeriveGetBooks.Service.userResponseUserResult'.
[解决办法]
引用有问题，重新引用试试