protected void OnSetLesson(object sender, EventArgs e) { try { if (!(sender is ImageButton)) return; var b = (ImageButton)sender; int userID; if (!Int32.TryParse(b.CommandArgument, out userID)) return; var userEvents = new UserWorkEvents(userID); var duration = TimeSpan.FromMinutes(45); userEvents.AddLatestClosedWorkEvent(duration, WorkEventType.TimeOff); FillUsersGrid(); } catch (Exception ex) { lblException.Text = ex.Message; lblException.Visible = true; } }