[SOLVED] Activity starts before milestone

Hello,
I have a problem of understanding on the use of milestones.

I want an activity begins after milestone (milestone = hardware delivery, activity = hardware configuration).
If I set a milestone and a successor activity, there is no problem in the schedule.
After, if I assign a resource to the activity, it starts before the milestone (the current day). The planning activity is configured as "as soon as possible".

Is it normal ?

No precisely, is after calculating planning that the problem happens.

Here, the planning before assigning the work.


And there, the planning after assigning work and calculated planning.


Only the fixed milestone, has a valid date.
Activities have working duration in hours.

The detail of first task