Thanks Andavari and rridgely for your help.
As far as I understand you, it is the normal use of CC, isn't it ?
I click on the "Fix the selected errors" button (translated from french) and then I click on the "Fix all the selected errors". CC seems to do its job, finishes by a box saying everything has been done and if I check later, all keys are all still here.
I've already try the fix "one by one" button : same