You're the one, thanks a lot

I have separated in 2 check,
- Chapter 1 OR Chapter 2 need to be checked
- Only Chapter 1 or Chapter 2, not together have to be checked
After
Code:
Set oSource = ThisDocument
I add :
Code:
'test si les chapter 1 ou 2 sont cochés
If oSource.SelectContentControlsByTitle("Chapter1").Item(1).Checked = False And _
oSource.SelectContentControlsByTitle("Chapter2").Item(1).Checked = False Then
MsgBox "Les cases 1 ou 2 doivent être cochées"
GoTo lbl_Exit
End If
'test si les chapter 1 et 2 sont cochés
If oSource.SelectContentControlsByTitle("Chapter1").Item(1).Checked = True And _
oSource.SelectContentControlsByTitle("Chapter2").Item(1).Checked = True Then
MsgBox "Les cases 1 et 2 ne doivent pas être cochées ensemble"
GoTo lbl_Exit
End If
I'm really happy to learn that