Shared Workbook Which Has 12 Worksheets

[Lobo1943]

have a shared workbook which has 12 worksheets and each Worksheet has to following VBA code to lock cells after data entry:
Private Sub Worksheet_Change(ByVal Target As Range)

Dim cl As Range

ActiveSheet.Unprotect

For Each cl In Target

If cl.Value <> "" Then

check = MsgBox("is this entry correct? This cell cannot be entered after entering a value.", vbYesNo, "Cell Lock Notification")

If check = vbYes Then

cl.Locked = True

Else

cl.Value = ""

End If

End If

Next cl

ActiveSheet.Protect


End Sub
This works fine when the Workbook is not shared, but when I Share the workbook the code doesn't perform. My question is, "is in possible to share a Wordbook and the code will perform as intended?" Meaning that after data is entered the cell is automatically locked, so other cannot either enter data or delete data.