Stopwatch is greying out undo

[Martina Hawkins]

Hi, I have a stopwatch which is working great except when a user opens a new workbook the undo function is unavailable. It becomes available again when the clock is stopped.
I have the code below in a module. Does this happen to anyone else?
Option Explicit

Dim NextTick As Date, t As Date, PreviousTimerValue As Date

Private Sub StartTime()
PreviousTimerValue = Calculations.Range("A1").Value
t = Time
Call ExcelStopWatch
End Sub

Private Sub ExcelStopWatch()
Calculations.Range("A1").Value = Format(Time - t + PreviousTimerValue, "hh:mm:ss")
NextTick = Now + TimeValue("00:00:01")

If Calculations.Range("A1").Value > Calculations.Range("B3") Then
With Sheet4.Shapes("TimeBox")
.Fill.ForeColor.RGB = RGB(0, 255, 0)
End With

End If

Application.OnTime NextTick, "ExcelStopWatch"
End Sub

Sub StopClock()
On Error Resume Next
Application.OnTime earliesttime:=NextTick, procedure:="ExcelStopWatch", schedule:=False
With Sheet4.Shapes("TimeBox")
.Fill.ForeColor.RGB = RGB(255, 0, 0)
End With
End Sub

Sub Reset()
On Error Resume Next

With Sheet4.Shapes("TimeBox")
.Fill.ForeColor.RGB = RGB(192, 192, 192)
End With

Application.OnTime earliesttime:=NextTick, procedure:="ExcelStopWatch", schedule:=False
Calculations.Range("A1").Value = 0
End Sub

 

[Martina Hawkins]

I've found the problem but not the solution. If I don't colour the shape it works. Has anyone a solution as to how to colour a shape not using vba.
Trying to use conditional formatting but can't get it figured out.

'If Calculations.Range("A1").Value > Calculations.Range("B3") Then

' With Sheet4.Shapes("TimeBox")
' .Fill.ForeColor.RGB = RGB(0, 255, 0)
' End With

'End If