Unable to delete an assignation in an activity - by: dnaton

Hello,

I have an activity, with 3 "sub-activites", like this




The "main" activity has 3 assignations, with no input work :




One of the "sub-activity" hase 4 assignations (3 are the same as the main activity, 2 are specific to the sub-activity




My problem appear when I want to delete one of the assigation of this sub-activity

When I try to delete Quentin, I have this message :



When I try to delete Adil, Vincent, I have the same message, except (1) that replace (4)
When I try to delete Sébastien or Jérôme, it works....

I don't understand why happend

No ressources has assigned work, or real work...and some ressources can be deleted, some other no

Can somebody explain me what I do that is not correct ?

Thanks