Outlook 2010 custom form + button + code = nothing

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Outlook

script

form

Hello,
I try to do a simple test in a custom form (task or calendar).
I add a button (GoButton), and add the following code (script editor):

Private Sub GoButton_Click ()
MsgBox ("Yop!")
End Sub

If I test directly the form, I click the GoButton and the window with "Yop!" appears.
If I publish the form and I associate as default form if I use the form when I press the GoButton... nothing happens (no "Yop !" messagebox).

Macro security is at least, I do not see where is the problem.

Anyone have an idea?
Thank you!
Azaone