Drag&Drop doesn't update the date field

Hi All,
i have installed Drupal (7.1.2), modules View (7.x-3.1) and FullCalendar (7.x-2.0-beta3) , as required. I have also created a dedicated content type 'Event', embedding a field Date.
My view shows correctly all the created events, but the drap&drop action on a specific event doesn't update the corresponding date fields into the database. There is no message, especially one from the function fullcalendar_update.
The action is made as administrator, with or without ajax settings, on Firefox/Aurora version.
Best regards
Fred