Worksheet_Change function

I am trying to get a Worksheet_Change function to run. I have one workbook with data and another with pivot tables. I need the function to run on change of a cell so I can update my pivot tables. I'm not sure why it won't run. I have it in 'ThisWorkbook'.

Here is my code:
Private Sub Worksheet_Change(ByVal Target As Range)

'Worksheets("Recycling Center").Unprotect Password:="cory"
If Not Intersect(Target, Range("H18")) Is Nothing Then
MsgBox "You changed cell H18."
End If

If Not Intersect(Target, Range("H18").EntireColumn) Is Nothing Then
MsgBox "You changed something in column H."
End If
'Worksheets("Recycling Center").Protect Password:="cory"

End Sub

Thanks in advance.
Corina