GridView数据绑定不工作

我有一个网格视图，它有一个对象列表的数据源。但它似乎在DataBind步骤中出现了问题。它不会在网站上显示任何内容。

List<StringTR> strResult_List = new List<StringTR>();
foreach (TSService.STs ST in ST_Returned_list) //I'm converting ST_Returned_list to StringResult as ST_Returned_list has some custom type fields and they are not working with Gridview
{
    strResult_List.Add(new StringResult(ST));
}
ResultsGridView.DataSource = strResult_List;
                    ResultsGridView.DataBind(); // this is where it is failing. when I step through it, it says "Step into: Stepping over method without symbols" 

public class StringResult
    {
         string str_SName { get; set; }
         string IPAddressUsed { get; set; }
         string BTypeUsed { get; set; }
         string SResult { get; set; }
        public StringResult(TestScriptsService.Sel_Test ST)
        {
                str_SName = ST.SName.ToString();
                IPAddressUsed = ST.IPAddressUsed;
                BTypeUsed = ST.BTypeUsed.ToString();
                SResult = ST.SResult.ToString();
        }
    }