I`m looking for a title of horror movie about haunted house - old orphanage

A family is moving to a big new house that have been an orphanage. The son (I think he was the only child) start to see a ghost of a dead boy in the nights. The ghost show the boy some way in the vaults of the house. The boy discover that the children from the old orphanage have been killed by two sanitarians. The ghosts of the children want revenge and somehow our boy finds the two guys and bring them to the house,something like that. There is a chase in the dark corridors under the house, the boy kills the one of the sanitarians. Finally the other one chase the boy in some high room in the house. The spirits appear then and the man (I cant remember if they push him down) falls throw the window and dies. On the last scene we see a lot of dead bodies on the ground next to the house. The bodies are of children and they waving goodbye.
I have seen this movie maybe 14-15 years ago and it scared the **** out of me. I have search a lot for it in IMBD but found nothing. It is NOT "The Orphanage'' by G. del Toro, I think is something close to his ''Devil`s backbone'' like script but it is NOT it. Please help me to find the title of this movie!

Your not alone!! I've been searching for this title for years. I watched it when i was a kid. I remember the "Head Master" of the Orphanage getting pushed out of the window. This was how the kids where murdered making it look like they where committing suicide. I am continuing my search for this film. I remember it being the most eerie movie ever or I may have just been young at the time.