Cancelling OnTime When Workbook Is Closed?

How to correct the code below so that OnTime is cancelled when the workbook is closed?

Error on bold line is Run-time error '1004': Method 'On Time' of object'_Application' failed

Code:
Public RollTime As Date, CalculateTime As Date, RefreshTradesTime As Date

Sub CancelOnTimeProcess()
SetTimesForRoll
With Application
.OnTime RollTime, "RollMacro", , False
.OnTime CalculateTime, "AutoCalculation", , False
.OnTime RefreshTradesTime, "UpdateLinks", , False

[Code] .......

CancelOnTimeProcess is being called when the user closes the workbook:

Code:
Private Sub Workbook_BeforeClose(Cancel As Boolean)
CancelOnTimeProcess
End Sub