如何在控制器事件中的会话变量中使用和存储数据

Question

public void MqttMsgPublishReceived(object sender, MqttMsgPublishEventArgs e)
{
    string ReceivedMessage = System.Text.ASCIIEncoding.ASCII.GetString(e.Message);

    if (ReceivedMessage.Contains("M2MType IO"))
    {
        Session["msg"] = ReceivedMessage;  // not storing data
    }
}

行

Session["msg"] = ReceivedMessage;

没有将数据存储到msg

我不知道为什么会这样。请告诉我如何在事件函数中使用会话变量。