Impossible to leave "manual" planning mode as some "real" planning exists

HI,

Which message ? ( not attached)
What the meaning of the last sentence ? Do not understand.

Sorry, but i still do not undersand your request about tthe link beetween, progress,  planning mode and fixed duration. Could you explain again. Thank U;

What is your matter ? Yes on fixed duration the progress could be calculated "manually" based on valided cost  or are you talking about the fact that progress  is calculated depending on the duration if no workload had been given ? On first case, you can integrate the progress of this single activity which  you do not master ( supplyer, another office, another team, ...) on your whole progress of the project to get a better real value than none.
On manual planning progress is only  calculated depending on the workdone compare to the whole one ( done + left) cause you have given and planified real workload by your own because you master ( you manage)  this activity.