The only think i can think of is that he has you on his ignore (enemies) list, which likely stops you from sending him messages (i really wouldn't know, because i have never ignored anyone, nor noticed that anyone has ignored me) but that would be my only idea.
(piilota) Pidä postilaatikkosi siistinä arkistoimalla tärkeät viestit ja käyttämällä säännöllisesti Poista kaikki -toimintoa. (pauloaguia) (näytä kaikki vinkit)