/// <summary>
        /// Raises the <see cref="E:System.Web.UI.Control.Init" /> event.
        /// </summary>
        /// <param name="e">An <see cref="T:System.EventArgs" /> object that contains the event data.</param>
        protected override void OnInit(EventArgs e)
        {
            base.OnInit(e);

            try
            {
                string groupMemberKey = PageParameter("gm");
                if (string.IsNullOrWhiteSpace(groupMemberKey))
                {
                    ShowError("Missing Parameter Value");
                }
                else
                {
                    var groupMemberService = new GroupMemberService();
                    var groupMember        = groupMemberService.GetByUrlEncodedKey(PageParameter("gm"));
                    if (groupMember == null)
                    {
                        ShowError();
                    }
                    else
                    {
                        groupMember.GroupMemberStatus = GroupMemberStatus.Active;
                        groupMemberService.Save(groupMember, CurrentPersonId);

                        nbMessage.NotificationBoxType = NotificationBoxType.Success;
                        nbMessage.Title = "Success";
                        nbMessage.Text  = GetAttributeValue("SuccessMessage");
                    }
                }
            }
            catch (SystemException ex)
            {
                ShowError(ex.Message);
            }
        }