Assigned Status force the planned date

Hi all,

I have to start by saying I'm stiil a newbi with ProjeQtOr ...
After reading the help and forums an issue is still there :
When I move the Task status to "Assigned", the "planned date" is forced to the current date. Even I use the manual or fixe planning
I was expecting to keep the "Validated date".

Any suggestion ? Do I have a wrong setup somewhere ?

Thanks in advance for your help

Vincent