A recursive procedure

Hello everyone and greetings!

I have concocted a procedure to control two (2) clocks for a chess game. On a sheet, I have 2 cells that contains the cumulative time spent by each player; I also have 2 buttons that each player must push in turn once their move is completed. Pushing one button activate the clock of the opponent while stopping the other clock.

All the code is in the sheet module (object).

Here is the code:
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Sheet1(Board)(Code)
Dim Clocks$, NextTick

Sub StartBlackClock()
'AND STOP THE WHITE CLOCK!

'Depress black's clock Button and popup white's clock button
If ActiveSheet.Shapes.Range(Array("Bevel 7")).Adjustments.Item(1) = 0 Then Exit Sub
ActiveSheet.Shapes.Range(Array("Bevel 7")).Adjustments.Item(1) = 0
ActiveSheet.Shapes.Range(Array("Bevel 6")).Adjustments.Item(1) = 0.15

'Stop the Ongoing time counter
On Error Resume Next
Application.OnTime NextTick, "UpdateClock", , False
Clocks = "B"
Call UpdateClock 'To start the B clock

End Sub
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Sub StartWhiteClock()
'AND STOP THE BLACK CLOCK!

'Depress white's clock Button and popup black's clock button
If ActiveSheet.Shapes.Range(Array("Bevel 6")).Adjustments.Item(1) = 0 Then Exit Sub
ActiveSheet.Shapes.Range(Array("Bevel 6")).Adjustments.Item(1) = 0
ActiveSheet.Shapes.Range(Array("Bevel 7")).Adjustments.Item(1) = 0.15

'Stop the Ongoing time counter
On Error Resume Next
Application.OnTime NextTick, "UpdateClock", , False
Clocks = "W"
Call UpdateClock 'To start the W clock

End Sub
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Sub UpdateClock()
'DIGITAL CLOCKS - there are 2: one for Blacks, one for Whites
If Clocks = "B" Then
'Set up the next event one second from now
NextTick = [BlackClock].Value + TimeValue("00:00:01")
[BlackClock].Value = [BlackClock].Value + TimeValue("00:00:01")
Else '"W" is implied
'Set up the next event one second from now
NextTick = [WhiteClock].Value + TimeValue("00:00:01")
[WhiteClock].Value = [WhiteClock].Value + TimeValue("00:00:01")
End If
Application.OnTime NextTick, "UpdateClock"
End Sub
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The Bold type statement just before End sub above is the one that presumably launches into a recursive. But it does not work.
Anytime I depress a button, the corresponding cell containing the time increments by 1 second, but that is all - no more action (with the recursive working it should update every second cumulatively until the other button is depressed).
My code structure was inspired by John Walkenbach's example ClockChart.xls; as a matter of fact it follows his exact logic
A picture of the actual Excel sheet also gives you an idea of what I am doing.

Could anyone tell me where I am going wrong in my code?

Notes: I use coding for range with [rangename] to replace the lenghty range("rangename")

Thank you in advance.

Corentint