can any one solve error please.

public string[] GetCompletionList(string prefixText, int count)
    {
      //  DB cn = new DB();
        conn();
        DataTable dt = new DataTable();
        DataSet ds = new DataSet();
       
        try
        {
          
            string text = "%" + prefixText + "%";
            cmd = new SqlCommand("select * from product where name like '" + text + "'", con);
            da = new SqlDataAdapter(cmd);
            ds = new DataSet();
            da.Fill(ds);


          //  ds = cn.getDataSet("select * from reg where Firstname like '" + text + "'", "reg");
        }
        catch
        {
        }
        finally
        {
          

        }
        dt = ds.Tables[0];

        //Then return List of string(txtItems) as result
        List<string> txtItems = new List<string>();
        String dbValues;
        String img;
        String email;
        foreach (DataRow row in dt.Rows)
        {
            //String From DataBase(dbValues)

            dbValues = row["Email"].ToString();
            
            //dbValues = dbValues.ToLower();
            //txtItems.Add(dbValues,);

            img = row["image"].ToString();
           img = img.Remove(0, 2);
            
            //txtItems.Add(img);
           
            
            txtItems.Add(AjaxControlToolkit.AutoCompleteExtender.CreateAutoCompleteItem(dbValues.ToString(), img.ToString()));


           // txtItems.Add(AjaxControlToolkit.AutoCompleteExtender.CreateAutoCompleteItem(dbValues.ToString()));
        }

        return txtItems.ToArray();

    }

   
    
}

dt=ds.table[0];