I think the problem here is that you phrase it as “...fan fiction using characters from the Harry Potter world...” That is not enough, since the archive moderators need to see a fandom disclaimer. So, I suggest something along the lines of “This is a work of fan fiction. Harry Potter is owned by J.K. Rowling...” and then the rest as you have it is fine.
Willow Darkling, forum moderator.
Edit: And I moved this to a more appropriate forum.