Proof of Ghosts, The Winchester Mystery House and the Missing Photo

In July of 2002 my family and I visited the Winchester Mystery House in San Jose, California. It is purported to be haunted. (meaning: ghosts or departed spirits inhabit the place)
I took many photos and despite my great desire to see one or capture a ghostly image on film. (I was still using film at the time) I was unsuccessful.
I did have a picture I took at my sons 3rd or 4th birthday that clearly showed what seemed to be a cloudy grandmotherly face smiling down upon him from near the ceiling.
At that time I always printed two copies of each photo. (each photo included the same strange image) I carefully put them into an envelope for safe keeping and of course misplaced them.
I tend toward skepticism in these matters but I keep an open mind. Here is an excellent piece from the Skeptical Inquirer on the subject of Ghost Photos.If anyone reading this post has a photograph or another piece of evidence that they feel to be proof of the existence of ghosts please let me know.
Later,
Paul Parducci