Having an issue altering the finish date for an activity

B
Braden B 👤 Member for 13 years

I have an activity in which I know the exact date it will finish, however I am having trouble adjusting the finish date in my schedule.

All predecessing activities have been completed, so it's not being pushed back because of that.

Additionally, I have set a "must finish"constraint on the date it will finish, along with an expected finish date that is the same. 

When I try and change the finish date I get an error message stating "Remain Finish Date cannot be earlier than Remain Start Date." My start date was over a month ago. Duration type is "fixed duration & units".

Any idea why it won't allow me to change the finish date?

Thanks very much,

B

R
Rafael Davila 👤 Member for 22 years 3 months

Any idea why it won't allow me to change the finish date?

  • Because as the software said, "Remain Finish Date cannot be earlier than Remain Start Date."

I suspect the Remaining Start Date is being delayed further than DD. But why Remain Start Date is delayed even when all predecessors have finished?

It might be that there is still an out-of-sequence link that is still active if the link have a lag value that have not elapsed completely. In such case Remaining Start will be delayed to the date where active lag will have completely elapsed.

Unfortunately most/none CPM software disclose Remaining Lag, not to mention Relationship Slack.

http://www.ronwinterconsulting.com/Making_CPM_Transparent.pdf

In-Progress Lag Report and Value: Remaining Lag should be displayed just as remaining duration is shown and editable. The CPM feature of Remaining Duration was added so that Schedulers could monitor and change this calculated duration result. Lags are to relationships what durations are to activities. Why should Remaining Lag calculations be discarded by the software instead of
saved and displayed? Why should we be unable to indicate that actual remaining lag is only 2 days instead of the calculated 4 days? Part of the reason CPM Schedules are so hard to understand is that fact that not all of the data used is displayed.

http://scheduleanalyzer.com/sa_long_theory.htm

The term “slack” as it concerns a CPM relationship is the amount of ‘unused’ time difference between the predecessor and the successor activities. This slack value has nothing to do with the float values or either of the two activities that it relates. It merely indicates how close each predecessor is to becoming the driving relationship for the successor activity.

Spider project have the option to setup out-of-sequence to ignore preceding links of activities finished but I still prefer to fix logic. No single out-of-sequence rule will correctly fix all possible occurrences.

Good luck,

Rafael

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