I am just wondering, how does your place's (country?) OI team selection work?

I am from Hong Kong and to join the HKOI selection process, we must register through our school. Unfortunately, my teacher did not confirm through the three confirmation emails and thus did not sign me up for the heat event, therefore I miss an annual chance to join the HKOI. Therefore, I am wondering if it is the same anywhere else, that you must register through your school? That sounds stupid to me but HKOI (hi tony) simply replied with "rules are rules". (I have joined the mirror of China OI first round selection and got decent grades but they won't let me join the second round of HKOI.)

Hope this makes sense, since I am probably leaving out details of the HKOI selection process.