Call a modal popup from a selected radiobuttonlist value

protected void BtnViewDetails_Click(object sender, EventArgs e)
   {
       //  get the gridviewrow from the sender so we can get the datakey we need
       Button btnDetails = sender as Button;
       GridViewRow row = (GridViewRow)btnDetails.NamingContainer;

       //  extract the customerid from the row whose details button originated the postback.
       //  grab the customerid and feed it to the customer details datasource
       //  finally, rebind the detailview
       this.sqldsCustomerDetails.SelectParameters.Clear();
       this.sqldsCustomerDetails.SelectParameters.Add("customerid", Convert.ToString(this.gvCustomers.DataKeys[row.RowIndex].Value));
       this.dvCustomerDetail.DataSource = this.sqldsCustomerDetails;
       this.dvCustomerDetail.DataBind();
       //  update the contents in the detail panel
       this.updPnlCustomerDetail.Update();
       //  show the modal popup
       this.mdlPopup.Show();
   }