[AccessD] Call AfterUpdate Event From Module

I'm going to add a calendar button adjacent to each date field throughout
many forms.  The code, a public function procedure, will be in a standard
module (in a library).  Each calendar button will call the function
procedure using a call from the OnClick event procedure of the button.  The
call in the event procedure is this:

     =CalendarButton("frmName","txtName",True)


The function is this:

Public Function CalendarButton(stgForm As String, stgDate As String,
blnAfterUpdate as Boolean)

    Dim frm As Form
    Dim txtDate As TextBox

    Set frm = Forms(stgForm)
    Set txtDate = frm.Controls(stgDate)

    If txtDate.Enabled = False or txtDate.Locked = True Then
        Set frm = Nothing
        Set txtDate = Nothing
        Exit Function
    End If

    txtDate = PopupCalendar(txtDate)

    '--- Call back to the control's AfterUpdate event for validation
    If blnAfterUpdate = True Then
        Call frm.txtDate_AfterUpdate   <------------ This line doesn't work.
        Call frm.txtCustomerDueDate_AfterUpdate  <-- Works, but doesn't
help.
    End If

    If Not IsNull(txtDate) Then
        SendKeys Chr(9)  '-- Tab Key
    End If

End Function


I need to call the field's AfterUpdate procedure (which is now Public) to
perform validation, which is different for different date fields.  Is there
a way to do this?

Thanks!
Dan Waters