Another additional information

If the Addin is already installed... the simple fact to run thos lines
create an Excel process that do not close... then I need to kill it through
task manager

Lines

Set appXL = CreateObject("Excel.Application")
If appXL.Application.Addins("addin.xla").Installed = True then
End if
set appXL = Nothing

As if the simple fact to manipulate the Addins collection was producing the
fact the Excel.exe do not close any more...

Thanks
Alain