error when update data to database using checkbox - asp.net-mvc

Question

i try to update my database using checkbox, when i delete data, my code is work. but when i update to add some value to database, i got some error.
**
Cannot insert explicit value for identity column in table 'HotelRoomFacility' when IDENTITY_INSERT is set to OFF.
**
this my code
my service
public void UpdateFacilityInHotel(List<int> FacilityIDs, int RoomTypeID)
{
List<HotelRoomFacility> hotelRoomFacilities = _HotelRoomFacility.AsQueryable().Where(f => f.RoomTypeID == RoomTypeID).ToList();
foreach (int newFacility in FacilityIDs)
{
if (hotelRoomFacilities.Where(h => h.RoomFacilityID == newFacility).Count() == 0)
{
HotelRoomFacility facility = new HotelRoomFacility
{
RoomFacilityID = newFacility,
RoomTypeID = RoomTypeID
};
_HotelRoomFacility.Add(facility);
}
}
foreach (HotelRoomFacility facility in hotelRoomFacilities)
{
if (FacilityIDs.Contains(facility.RoomFacilityID) == false)
_HotelRoomFacility.Delete(facility);
}
_HotelFacilityRepository.CommitChanges();
}
my controller
public ActionResult EditRoom(int RoomTypeID)
{
ViewBag.hotel = _hotelService.GetByID(_HotelID).HotelName;
//var roomType = _hotelService.ShowRoomByID(RoomTypeID);
//return View(roomType);
List<EditRoomTypeViewModel> editRoomTypeViewModel = _showRoomByIDService.ShowRoomByID(RoomTypeID);
return View(editRoomTypeViewModel.FirstOrDefault());
}
[HttpPost]
public ActionResult EditRoom(EditRoomTypeViewModel typeRoom, FormCollection forms)
{
List<string> IDs = forms["FacilityIDs"].Split(',').ToList();
List<int> FacilityIDs = new List<int>();
foreach (string ID in IDs)
{
FacilityIDs.Add(Convert.ToInt32(ID));
}
_showRoomByIDService.UpdateFacilityInHotel(FacilityIDs, _HotelID);
return EditRoom(_HotelID);
var x = _hotelService.UpdateRoom(typeRoom.RoomTypeID, typeRoom.RoomTypeName, typeRoom.RoomTypeDescription);
if (x != null)
{
return RedirectToAction("Room");
}
return View(typeRoom);
}
my view
#model XNet.Repository.Model.EditRoomTypeViewModel
#{
ViewBag.Title = "addRoom";
}
<h2>Edit Room</h2>
#using (Html.BeginForm())
{
#Html.ValidationSummary(true)
<fieldset>
<legend>Isikan Data</legend>
<div>
#Html.Label("Hotel Name")
</div>
<div>
#ViewBag.hotel
</div>
<br />
<div>
#Html.HiddenFor(model => model.RoomTypeID)
</div>
<br />
<div>
#Html.Label("Room Type Name")
</div>
<div>
#Html.EditorFor(model => model.RoomTypeName)
#Html.ValidationMessageFor(model => model.RoomTypeName)
</div>
<br />
<div>
#Html.Label("Room Type Description")
</div>
<div>
#Html.TextAreaFor(model => model.RoomTypeDescription)
#Html.ValidationMessageFor(model => model.RoomTypeDescription)
</div>
<br />
<table>
<thead>
<tr>
<th>Facility Name</th>
<th> is available</th>
</tr>
</thead>
<tbody>
#foreach (var facility in Model.facilitiesInRoom)
{
<tr>
<td>
#(facility.RoomFacilityName)
</td>
<td style="text-align:center;">
<input type="checkbox" #(facility.RoomFacilityAvailable ? " checked=checked" : null) name="FacilityIDs" value="#facility.RoomFacilityID" />
</td>
</tr>
}
</tbody>
</table>
<br />
<p>
<input type="submit" value="Save" />
<input style="width:100px;" type="button" title="EditHotelDetail" value="Back to Detail" onclick="location.href='#Url.Action("Index", "Hotel") '" />
</p>
</fieldset>
}
Here is the database diagram