Maybe because it was a Harry Potter cover ?
I wrote to Alan Rickman twice. First time talking about HP in my letter (and of course all the others movies I love, not only HP) and with a photo of professor Snape. And got a negative answer for his assistante (telling he was too busy, and working abroad).
Second time without talking about HP and with neutral photo of him, and I've got an autograph...so maybe it's because of "Harry Potter" ??
It was TTM, but maybe even IP he doesn't like to sign Harry Potter's items ?
I can be wrong.
