[otrs] Opening .ics files sent by calendar module in Outlook 2003

Hello OTRS fans, I'm testing the calendar module. Every event added to the calendar is sent to the agent by e-mail, with a .ics file attached to it. I can open the file within Outlook 2003, but can't save it in the Outlook Calendar. It says: "This meeting does not appear in the calendar. It may be moved or deleted." (or something like that in my French version). Did you manage to use OTRS .ics files with Outlook ? How ? Thanks and regards, Regis