Data Validation Dynamic Range Moves Range Instead of Expanding Range - vba

Question

In Excel, I have a Data Validated range using the OFFSET() function that I'm hoping to dynamically add information to that I can then select in a drop down list. I have a VBA macro that I'm adding information to this list from and instead of expanding the list from $L$10:$L$230 to $L$10:$L$231, it shifts my list down to $L$11:$L$230. What am I doing incorrectly in my Named Range or Data Validation to not make this work? Or does it have something with using VBA to add to the range that causes it to work incorrectly?
"Rooms" in my Name Manager Refers To:
=OFFSET(Sheet1!$L$10,0,0,COUNTA(Sheet1!$L:$L),1)
My Data Validation Drop Down Souce:
=Rooms
My "insert" Macro to add to the list:
Sub insert()
'
' insert Macro
'
'
Range("A2:E2").Select
Selection.Copy
Sheets("Sheet1").Select
Range("L10:P10").Select
Selection.insert Shift:=xlDown
Sheets("INSERT NEW ROOM").Select
ActiveWindow.SmallScroll Down:=-18
Range("A2").Select
End Sub
I also have a "Sort" VBA included in my Sheet1 for every time a new instance is added from the "INSERT NEW ROOM" tab.
Private Sub Worksheet_Change(ByVal Target As Range)
On Error Resume Next
If Not Intersect(Target, Range("L9:L500")) Is Nothing Then
Range("L9").Sort Key1:=Range("L10"), _
Order1:=xlAscending, Header:=xlYes, _
OrderCustom:=1, MatchCase:=False, _
Orientation:=xlTopToBottom
End If
End Sub

Answer 1

This happens because your insert macro changes the range your named range formula refers to, just like it would any normal formula.
The formula has a reference to cell $L$10. When you execute
Range("L10:P10").Insert Shift:=xlDown
any formula, including the named range formula, that referes to a cell on or below row 10 will be updated to refer to a cell one row down (ie $L$11 in this case)
You can fix this by changing your named range formula to this
=OFFSET(Sheet1!$L$1,9,0,COUNTA(Sheet1!$L:$L),1)
Notice it now refers to cell $L$1 so is not affected by the insert.
Note:
You insert macro could do with some work
Try this instead
Sub InsertRooms() ' renamed to avoid using a built in function name
Range("A2:E2").Copy
Worksheets("Sheet1").Range("L10:P10").insert Shift:=xlDown
Application.CutCopyMode = False
End Sub