[otrs] change customer is not taken into account in the notifications

Hi, I,ve got OTRS 3.0.11 and i have a problem. In a ticket, i change the customer (in the view ticket, button customer) I have notifications sent to customer but these notifications are sent to the old customer and not the new one. In the view ticket, part "Ticket Information", i have the good customer. Where am I wrong ? -- Zaki CHELLAH