I shouldn't have to call someone to make sure that he (or she, no gender bias on this one) is in his office for a meeting. In addition, when I get down to his office and see him come out of a conference room, he then should not immediately go into someone else's office, thus becoming unavailable. Then he should not stay in that other person's office for ten minutes, making me trek back up to my own desk and leave a semi-nasty voicemail message.