System.Data.DataRowView在文本框中，而不是默认值

请有人帮助我，为什么我得到"System.Data "。DataRowView"在我的文本框中开始，而不是"44"，这是我期望看到的?如果从下拉列表中再次选择它，那么它会为我填充字段。我试着看了很多论坛

再次谢谢你

private void E164Convertor_Load(object sender, EventArgs e)
        {
            DataTable dt = new DataTable();

            DataColumn dc1 = new DataColumn("CountryName");
            DataColumn dc2 = new DataColumn("CountryCode");

            dt.Columns.Add(dc1);
            dt.Columns.Add(dc2);
            dt.Rows.Add("United Kingdom" ,"44");
            dt.Rows.Add("United States" , "1");
            cbxctry.DataSource = dt;
            cbxctry.DisplayMember = "CountryName";
            cbxctry.ValueMember = "CountryCode";
        }
        private void cbxctry_SelectedIndexChanged(object sender, EventArgs e)
        {
         txtctrycode.Text = cbxctry.SelectedValue.ToString();
        }