Dirty event not firing on Access 2007 form - ms-access

Question

I have a bound pop up form with a Clear data button. It runs the Undo command.
The Form_Current event sets this button's enable property to False.
The Form_Dirty event sets this button's enable property to True.
The button's property is always set to False even after I enter data into the form. I think this is because my Form_Load event is populating two fields. One is passed from the main form as an OpenArgs, the other is the unique ID which is calculated based on the OpenArgs value.
Any suggestions as to how to get the Dirty event to activate under these circumstances? If not, then an alternative approach perhaps?
Thanks in advance.
Code below:
Private Sub cmdUndoChanges_Click()
CustID_temp = Me!CustID
FacNo_temp = Me!Unique_ID
DoCmd.RunCommand acCmdUndo
Me!CustID = CustID_temp
Me!Unique_ID = FacNo_temp
End Sub
Private Sub Form_Current()
Me!cmdUndoChanges.Enabled = False
End Sub
Private Sub Form_Dirty(Cancel As Integer)
Me!cmdUndoChanges.Enabled = True
End Sub
Private Sub Form_Load()
Dim test As Integer
Me!CustID = OpenArgs
test = DCount("Unique_ID", "tbl_Table2", "CustID = '" & Me!CustID & "'")
If IsNull(Me!UNIQUE_No) Then
test = test + 1
Me!Unique_ID = CustID & "-" & test
MsgBox "No Previous Data"
Else
' these will be turned back on when the user selects the
' modify data button or add new data button.
For Each ctl In Me.Controls
Select Case ctl.ControlType
Case acTextBox, acComboBox, acOptionGroup, acCheckBox
ctl.Locked = True
ctl.BackColor = 15066597
Box40.BackColor = 15066597
End Select
Next ctl
End If
MsgBox Me!Unique_ID
End Sub

Answer 1

Have you tried Form_BeforeInsert() instead of Form_Dirty()?

Answer 2

I found another case where the Form_Dirty event never fires, the hard way. I thought I'd add it here since this is the top search result for the "not firing" question.
If your Form_Load function does anything to change the value of an existing record, the form will be set to dirty immediately, apparently before the logic that fires the event begins to run. Because of that there will never be an event if other data on the form is changed.
We had a "smart" Save button that was disabled until Form_Dirty fired. After I added a fixup to Form_Load for old records with a junk field, editing those records no longer ever enabled the Save button.