private void LoadAvailability() { // If if (comboBoxDates.SelectedIndex < 0 || comboBoxTimeSlots.SelectedIndex < 0) { return; } DateTime selectedDateTime = bookableDateTimes[comboBoxDates.SelectedIndex]; string selectedTimeSlot = comboBoxTimeSlots.Items[comboBoxTimeSlots.SelectedIndex].ToString(); timeSlots = SqliteDataAccess.LoadTimeSlots(selectedDateTime.ToShortDateString(), selectedTimeSlot); foreach (Button button in reserveTimeSlotButtons) { button.Enabled = true; } foreach (TimeSlotModel timeSlotModel in timeSlots) { if (reserveTimeSlotButtons.ElementAtOrDefault(timeSlotModel.Roomid - 1) != null) { MessageBox.Show(timeSlotModel.Booked.ToString()); reserveTimeSlotButtons[timeSlotModel.Roomid - 1].Enabled = false; } } }