Are you a JET?
That doesn't matter. I often get the same treatment...basically some teachers will say good morning, some will actually engage in conversation (

), and many will act as if I don't even exist. Got used to that a long time ago.
I also love it when the teachers who never even acknowledge my presence will go to a (Japanese) English teacher if they want (usually it's "need") to say something to me. These people all know I can speak some Japanese, yet they never communicate with me directly.