Attempting to Reschedule

Since I'm unable to meet with Mr. Cooper on Thursday the 10th, I called him to ask to reschedule. I believe attempting to reschedule had offended him since I called after the meeting time and date, so I will be out of a possible interview with him. I'm really disappointed about this as I was looking forward to seeing his workshop, but it's completely expected as I was disrespectful by asking to move the date after it had already happened. This is definitely something to learn from, and if I plan on interviewing anyone else in my life, I should definitely remember to ask to reschedule BEFORE the date.