Ammend macro to keep an additional sheet unhidden

[DLJ98]

I have a spreadsheet that hides other sheets depending on the value of one of my data validations, however I can't work out how to adjust my code currently written to keep the costing sheet from hiding every time I adjust the data validation (other than naming it with all the possible outcomes of my data validation). The code is below:

On the Worksheet it is:

Private Sub Worksheet_Change(ByVal Target As Range)
  If Target.Address = Range("SelectType").Address Then
    Select Case Target.Value
      Case "Admin Lists"
        ShowAllSheets
      Case ""
        'do nothing
      Case Else
        ShowSelSheets
    End Select
  End If
End Sub

And then the general declarations are:

Option Explicit
Sub ShowAllSheets()
Dim ws As Worksheet
For Each ws In ActiveWorkbook.Sheets
  ws.Visible = xlSheetVisible
Next ws
End Sub

Sub ShowSelSheets()
Dim ws As Worksheet
Dim strType As String
strType = Worksheets("Chiller Selection").Range("SelectType").Value
For Each ws In ActiveWorkbook.Sheets
  If InStr(1, ws.Name, strType) > 0 Then
    ws.Visible = xlSheetVisible
  Else
    If ws.Name <> "Chiller Selection" Then
      ws.Visible = xlSheetHidden
    End If
  End If
Next ws
End Sub