VBA is stopping me from being able to undo

[FraserMc97]

Hi

So some of the excel wizards on here have created some coding for me to count coloured cells from conditional formatting however I have just realised that I can not undo anything because of this!

I'm not sure whether it is the following module:

Function ColorFunction(rColor As Range, rRange As Range, Optional SUM As Boolean)
    Dim rCell As Range
    Dim lCol As Long
    Dim vResult
    lCol = rColor.DisplayFormat.Interior.ColorIndex
    If SUM = True Then
        For Each rCell In rRange
            If rCell.DisplayFormat.Interior.ColorIndex = lCol Then
                vResult = WorksheetFunction.SUM(rCell, vResult)
            End If
        Next rCell
    Else
        For Each rCell In rRange
            If rCell.DisplayFormat.Interior.ColorIndex = lCol Then
                vResult = 1 + vResult
            End If
        Next rCell
    End If
    ColorFunction = vResult
End Function

Thanks