Unexpected Late Finish, Slack, or critical path in Project

MORE INFORMATION

When a task has a FNLT constraint, the constraint date becomes the new Late Finish date for the task, even if the constraint date is later than the scheduled finish date for the task, or is later than the project finish date.

Besides the Late Finish field, the Critical and Total Slack fields' calculations can be affected by a FNLT constraint, as described below:

• Late Finish: The Late Finish date is the latest date to which a task can be delayed without affecting the project finish date or the last constraint date, whichever is later.
  
  
• Critical: A task will display "Yes" in the Critical field if delaying the task will affect the project finish date or the last constraint date, whichever is later.
  
  
• Total Slack: The number of days displayed in the Total Slack field reflects the amount of time a task can be delayed without affecting the project finish date or the last constraint date, whichever is later.

Example

To see an example of this behavior, follow these steps:

1. In a new project file, create a task with one-day duration.
2. Select the task.
3. On the Project menu, click Task Information, and then click the Advanced tab.
4. Under Constrain Task, in the Type list, click Finish No Later Than.
5. Under Constrain Task, in the Date box, select a date that is two days later than the task's finish date.
6. Click OK.
7. On the View menu, point to Table and then click Schedule.
8. Scroll the table until you see the Late Finish and Total Slack fields.

You will notice the task's Late Finish date is two days later than the task's finish date, and the value of Total Slack is 2 days even though it is the only task in the project.