VBA to check if cell changed

I am trying to run a macro when user clicks button it checks if a cell value changed, if so run code to something

however my code stops on line 3 (first if statement) gives me run-time error ' 424' object required

Code:

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Private Sub DONE_Click()    Dim cell As Range
If Not Intersect(Target, Range("B6")) Is Nothing Then
For Each cell In Target
If cell.Value <> "" And cell.Value <> prevValue Then


'Consildates loose parts list by hiding cells containing zero value
    For a = 8 To 298
        If Worksheets("LoosePartsList").Cells(a, 2).Value = "0" Then
            Worksheets("LoosePartsList").Rows(a).Hidden = True
        End If
    Next
'Saves file in current folder file is in with new file name
    Dim FName As String
    Dim currentpath As String
    FName = Worksheets("LoosePartsList").Range("A1")
    currentpath = ThisWorkbook.Path & "\" & FName
    ActiveWorkbook.SaveAs FileName:=currentpath


Else
MsgBox "Please change the revision level and click ALL CALCUATIONS DONE again", , "REVISION LEVEL NOT CHANGED"
End If
Next cell
End If

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Target is a variable that normally is defined in e.g. the Worksheet_Change routine (it is passed as an argument to the routine). In your sample code, Target is undefined and thus empty. Therefore the For loop fails as there is nothing to loop through.