In Microsoft Project, when you type a start or finish date for a task in Network Diagram view or Task Form view, the task may be scheduled to the next working day without notification.
When you enter a start or finish date in Network Diagram view or Task Form view that is a nonworking day for a task, the date is automatically changed to the next working day.
If you enter a date that is a nonworking day in another view, such as the Gantt Chart view, the Planning Wizard will notify you that the day you entered is a nonworking day. This message does not appear in the Network Diagram or Task Form views because these views have fewer events that will be displayed by the Planning Wizard than other views.
To work around this behavior, type start or finish dates in a view other than the Network Diagram or the Task Form views. For example, type start or finish dates in Gantt Chart view.
Microsoft has confirmed that this is a problem in the Microsoft products that are listed at the beginning of this article.