Microsoft KB Archive/66673

Project Err Msg: Late Date Before Scheduled Date in Task X

PSS ID Number: Q66673 Article last modified on 10-20-1995

1.00 | 1.10

WINDOWS | MACINTOSH

= SUMMARY =

Microsoft Project for Windows and Macintosh generates the following error message

Late date before scheduled date in task X. For more information, press F1 for help.

when negative slack develops in task X. Negative slack means that the scheduled finish date for the task is too late for the project to finish as scheduled.

= MORE INFORMATION =

The “late date” message alerts you that there is not enough slack in the schedule to finish task X before some constraint date you have established.

The task X named in the error message is then forced against some limit, such as the project start date, or a successor task with a constraint. Because Project cannot adjust the scheduled start date of task X to a date that would allow the project to finish as scheduled, negative slack is introduced. In this instance, negative slack is the period of time by which task X would have to be moved to allow the project to finish on time.

Steps to Reproduce Message
The following example will produce the “Late date…” message, and illustrate the most common condition that leads to it:


 * 1) Open Project and enter three tasks that each have a five-day duration.
 * 2) Link the three tasks together in a finish-to-start relationship.
 * 3) Select task 3 and give it a Must Start On constraint.
 * 4) Select task 2 and change its duration to 10 days.

At this point, the “Late date…” message will be displayed. Notice that task 2 is referred to in the error message, but the task that is causing the conflict is task 3. In this case, task 3 has a constraint that prevents it from being moved.

The duration specified for task 2 has caused a dilemma. Task 3 cannot be moved forword because of the constraint that is set for it, nor can task 1 be moved backword because it would then be scheduled before the project start date.

Negative slack has been introduced to the project. As an example of how to correct the problem, select task 3 and change its constraint to As Soon As Possible. Project will now recalculate the project to resolve the conflict (task 3 will be rescheduled to a later date).

Items to Check to Resolve the Conflict

 * 1) Check the actual start and finish dates for the task and its successors. To display tasks that have started, but not finished, apply the In Progress filter to the Task Sheet or Gantt Chart. To display the dates and slack for each task, apply the Schedule table to the Task Sheet or Gantt Chart.
 * 2) Check the constraints for the task and its successors. To display tasks with constraints other than As Soon as Possible, apply the constrained filter to the Task Sheet or Gantt Chart. Note that an actual start date acts as an implied Must Start On constraint. An actual start date will be set if the Options Set Actual command is used, or if progress (percent complete) is shown for a task. Even if progress is reset to zero, an actual start date remains. To reset the actual start date, select and delete it.

The Gantt Chart Format Palette command can be used to display negative slack. Specify the start point as Negative Slack and the end point as Scheduled Start.

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= Additional reference words: 1.0 1.00 1.1 1.10 =

Copyright Microsoft Corporation 1995.