Sorry again, but this time the declined flag was about this answer that was deleted for an unknown reason.
So I flagged it by calling a moderator (there wasn't another flag that would fit better) and explaining that the deleted answer was correct, so it should be undeleted.
However, the flag was declined for the reason: "flags should only be used to make moderators aware of content that requires their intervention". That's exactly what I did: I wanted to make a moderator aware of this correct content that needed a intervention (undelete).
Anyway, the answer was actually undeleted so I do not understand why this flag was declined.