MySQL DataReader - Checkboxlist Data Retrieve

Question

HI,
   I have checkboxlist in aspx page.It fills from database while run application.I use Edit link button.Now i use MySQL reader to read data from database.

 txtPFirstName.Text = dr[3].ToString();

                    txtPMiddleName.Text = dr[4].ToString();

                    txtPLastName.Text = dr[5].ToString();

                    

                    CheckBoxList2.SelectedValue = dr[29].ToString();

For textbox it reads the data correctly.But in checkboxlist the data is not retrieved from database.How I retrieve data from database in to Dropdownlist?Can anyone help me to do this?