Planned dates will be calculated by planning depending on assignements / resources availability / contraints.
It you want to "fix" a task, use corresponding planning mode.

thank you.

but I don't understand what you mean.

As you can see in the attached document my valided date is upper that the automatic planified time.

I don't jnow how to do your explication

With file is better 🙂

Possibly you did not understand how projeqtor plans tasks
Have a look at user manual for better understanding on the subject.

Projeqtor does not "draw" a gantt, it calculates it, so your validated dates are just for control that your planned date respect what you committed with your customer.
Validated dates are not taken into account for planning calculation axcept if you chose planning mode "regular between dates" or other "regular ..."

HAHAHAHHA RTFM !!! 🙂

You're right I didn't read the user manual 😉

I'll do that i promise! 🙂