Again, this is why you 1) Start from the 'respect' angle. 2) Suggest an alternate time so that it can work. 3) Leave a paper trail. I would only involve a m

Again, this is why you 1) Start from the 'respect' angle. 2) Suggest an alternate time so that it can work. 3) Leave a paper trail. I would only involve a manager if it became a serial issue and you've made your concerns clear and in writing. Whether you come off as disinterested, not a team player, or just busy and the other person isn't willing to respect your schedule is up to you. But it all depends on you.