selected index property of radiobuttonlist

See more:

C#

I am developing a online exam project. For the option i took a radiobutton list and binding it dynamically.
The problem is that when i use the selected index property of radiobuttonlist, it is not giving it correct value on selecting a option.
Here is my code behind code:

sql = "select Question_no,Question ,Option1,Option2,Option3,Option4,Question_Image from Contact2 where Question_no=" + nextq + "";
            ds = cn.SelectDS(sql);
            if (ds.Tables[0].Rows.Count > 0)
            {

                lblqno.Text = ds.Tables[0].Rows[0]["Question_no"].ToString();
                lblqstn.Text = ds.Tables[0].Rows[0]["Question"].ToString();
                RadioButtonList1.ClearSelection();
                RadioButtonList1.Items.Clear();
                RadioButtonList1.Items.Add(ds.Tables[0].Rows[0]["Option1"].ToString());
                RadioButtonList1.Items.Add(ds.Tables[0].Rows[0]["Option2"].ToString());
                RadioButtonList1.Items.Add(ds.Tables[0].Rows[0]["Option3"].ToString());
                RadioButtonList1.Items.Add(ds.Tables[0].Rows[0]["Option4"].ToString());
                Image1.ImageUrl = ds.Tables[0].Rows[0]["Question_Image"].ToString();
            }


Please help me