C#出现invalidcastexception如何解决？

有没有大佬遇到这种问题？？？拜托拜托

namespace try1
{
    /// <summary>
    /// MainWindow.xaml 的交互逻辑
    /// </summary>
    public partial class MainWindow : Window
    {
        public MainWindow ()
        {
            InitializeComponent ();
            DispatcherTimer timer = new DispatcherTimer ();
            DateTime.Now.ToString ();
        }

        private void button_Click (object sender, RoutedEventArgs e)
        {


            ResultMessage msg = MWRDemoDll.MifareRFEYE.Instance.Search ();
            if (msg.Result == Result.Success)
            {
                //连接和寻卡
                lstshuju.Items.Add ("连接成功");
                lstshuju.Items.Add (msg.OutInfo);
                lstshuju.Items.Add ("寻卡成功");
                lstshuju.Items.Add (msg.Model);


                lstshuju.Items.Add (DateTime.Now);

            }
            else
                lstshuju.Items.Add (msg.OutInfo);


            //写卡
            string databuff = txtwenben.Text.Trim ();
            int total = 16;
            int len = GetStringCharLen (databuff);
            if (len < total)
                databuff = databuff.PadRight (total);
            byte[] data = Encoding.Default.GetBytes (databuff);
            ResultMessage msg1 = MWRDemoDll.MifareRFEYE.Instance.Write (CardDataKind.Data1, data);
            lstshuju.Items.Add (msg.OutInfo);

            ResultMessage msg2 = MWRDemoDll.MifareRFEYE.Instance.Read ();
            if (msg.Result == Result.Success)
            {
                //读卡
                lstshuju.Items.Add ("读卡成功");
                int n = lstshuju.Items.Add (Encoding.Default.GetString (((byte[])msg.Model)).Replace ("\0", ""));
                lstshuju.Items.Add (DateTime.Now);
            }
            else
                lstshuju.Items.Add (msg.OutInfo);


             }


        //将写卡栏里面的文字转化成计算机语言在显示
        public static int GetStringCharLen (string str)
        {
            int count = 0;
            Regex regex = new Regex (@"^[\u4E00 - \u9FA5]{ 0,}$");
            for (int i = 0; i < str.Length; i++)
            {
                if (regex.IsMatch (str[i].ToString ()))
                {
                    count += 2;
                }
                else
                {
                    count += 1;
                }
            }
            return count;
        }
    }
}

```![图片说明](https://img-ask.csdn.net/upload/202007/05/1593937430_815764.png)
这是debug后的错误

提示很清楚，msg.Model已经是字符串了，不能强制转换成byte[]类型