ThisWorkbook code not hiding named sheets

Hi, I have a seemingly simple problem but I can't seem to get around it. Perhaps someone else could enlighten me. When the user closes the workbook, I would like all worksheets except Inputs, SummaryOutput and DetailedOutput to be hidden. My attempt at the code is below:

Private Sub Workbook_BeforeClose(Cancel As Boolean)
Dim ws As Worksheet

Application.EnableEvents = True

For Each ws In ActiveWorkbook.Worksheets
If Not ws.Name = "Inputs" Or Not ws.Name = "SummaryOutput" Or Not ws.Name = "DetailedOutput" Then
ws.Visible = xlSheetHidden
End If
Next ws

ThisWorkbook.Save
End Sub

It's giving me a runtime error 1004- any ideas why? Any help would be greatly appreciated!

Does this work in place of your For/Next loop

For Each ws In ActiveWorkbook.Worksheets
    If Not (ws.Name = "Inputs" Or ws.Name = "SummaryOutput" Or ws.Name = "DetailedOutput") Then
       ws.Visible = xlSheetHidden

    End If
Next ws

Another possible issue is that VBA is case sensitive by default so the string comparisons may not match the actual name of the worksheets - either convert to same case (upper/lower) to compare or include

Option Compare Text

in the General Declarations section of the module.

Actually BigBas solved it! The For loop needed brackets as suggested- many thanks to all for your help.