Error: The macro or function set to the BeforeUpdate or ValidationRule property for t

I have a subform within a form. If the total payments in the subform is > the DolAmt in the form, i would like to set the payment in the subform to 0. I do a recalc to ensure that the total payments showing in the main form (which - Sum(payments) in subform gets recalculated. This is all happening after an Apply check has been clicked to indicate that the payment should be applied to the Dolamt in the main form

But I keep getting the msg:
Error: The macro or function set to the BeforeUpdate or ValidationRule property for this field is preventing the database from saving the data in the field

on the line where I reset me.Payment = 0 after the Cancel = True.
There are no validation rules on the payment field
Any advice would be much appreciated!!

Code is below

Private Sub Apply_BeforeUpdate(Cancel As Integer)
If Me.Apply = True Then
If Me.AmtDue > [Forms]![Customer Payment Form]![DolAmt] Then
Me.Payment = [Forms]![Customer Payment Form]![DolAmt]
Else
Me.Payment = Me.AmtDue
End If
Me.Paid = Me.PrePaid + Me.Payment
Else
Me.Payment = 0
Me.Paid = Me.PrePaid
End If
Me.Recalc
If Me.TotPayment > [Forms]![Customer Payment Form]![DolAmt] Then
MsgBox "Total applied cannot be greater than check amount!", vbExclamation, ""
Cancel = True
Me.Payment = 0
Me.Paid = Me.PrePaid
Me.Recalc
End If
End Sub
Private Sub Payment_BeforeUpdate(Cancel As Integer)
If Me.AmtDue < 0 Then
MsgBox "Total payment cannot be greater than amount due!", vbExclamation, ""
Cancel = True
End If
If [Forms]![Customer Payment Form]![FraCheckCredit] = 1 Then
If Not IsNull(Me.Payment) Then
If (Me.TotPayment) + Me.Payment - Me.Payment.OldValue > [Forms]![Customer Payment Form]![DolAmt] Then
MsgBox "Total applied cannot be greater than check amount!", vbExclamation, ""
Cancel = True
End If
End If
Else
If (Me.TotPayment) + Me.Payment - Me.Payment.OldValue > Forms![Customer Payment Form]![Customer Payment Apply Credits subform].Form![Amount] Then
MsgBox "Total applied cannot be greater than credit amount!", vbExclamation, ""
Cancel = True
End If
End If

End Sub

What is the purpose of using the BeforeUpdate Event in the Apply check box? I would think that using the AfterUpdate will correct the condition. The apply check box is a true/false condition and your msgbox is trying to cancel before it is even updated. If you need to use the before update event for the check box then move the msgbox to after update.

lwells