Macro and grouping not working in Protected sheet

Hello,
I have the following macro code in my "Overview" excel sheet. I recorded the macro and it works perfectly.

The problem is that i have grouped some fields and after the sheet is protected, the grouping doesnt work anymore.
It says remove the protection and try again. I have used no password to protect the file.

Sub Add_Row_Sort()
'
' Add_Row_Sort Macro
' Add a row and sort by deadline and priority
'

'
    Application.ScreenUpdating = False
    ActiveSheet.Unprotect
    Range("B9:Y9").Select
    Selection.ListObject.ListRows.Add (2)
    ActiveWorkbook.Worksheets("Overview").ListObjects("Table1").Sort.SortFields. _
        Clear
    ActiveWorkbook.Worksheets("Overview").ListObjects("Table1").Sort.SortFields. _
        Add Key:=Range("Table1[Deadline]"), SortOn:=xlSortOnValues, Order:= _
        xlAscending, DataOption:=xlSortNormal
    ActiveWorkbook.Worksheets("Overview").ListObjects("Table1").Sort.SortFields. _
        Add Key:=Range("Table1[Prio]"), SortOn:=xlSortOnValues, Order:= _
        xlAscending, DataOption:=xlSortNormal
    With ActiveWorkbook.Worksheets("Overview").ListObjects("Table1").Sort
        .Header = xlYes
        .MatchCase = False
        .Orientation = xlTopToBottom
        .SortMethod = xlPinYin
        .Apply
    End With
    ActiveSheet.Protect
    Application.ScreenUpdating = True
    Range("B8").Select
End Sub

Thanks in advance,

Ranju