Please, if you say you’re going to do something, do it. Whether it’s a tech workshop, a family function, a kids party or a meeting with a friend. If you say you’re going to be somewhere, be there. And if something comes up, and you can’t be there, please have the courtesy to let someone know so that the organisers know who to expect, or even so your place can be offered to someone else.
It’s just common courtesy.