The Requiem song

It doesn't work even if a corpse is there. I've been able to sing it only once and after I always had the same "no corpse" message.. |34%hp 68%m 100%mv 11099tnl 5 AM civilized| look A white square You are standing on what appears to be a huge chessboard. Everything is well-lit, but you cannot locate the source of this light. Distances seem hazy, but occasionally you can catch a glimpse of the "pieces". [Exits: north east south] The bludgeoned corpse of a white pawn lies here. The sliced-off leg of a white pawn is lying here. |34%hp 68%m 100%mv 11099tnl 5 AM civilized| sing requiem There is no corpse here to sing your melody over. |34%hp 60%m 100%mv 11099tnl 5 AM civilized| sac corpse The gods give you 10 copper coins for your sacrifice of the corpse of a white pawn. |34%hp 60%m 100%mv 11099tnl 5 AM civilized|