Could it be you just recently started to play the clarinet? I had an adult student a while a go who had been playing for two years and wasn't able to play form high b on. Sometimes you heard a note (Aw, that hurt) and other times there was just this buzzing sound.
First make sure your other notes sound oke, and then you start working upwards. If you say you have problems with a, start with g. Play a long g, until you think your embouchure is really relaxed and then just lift your finger to play a. So, PLAY SLURRED NOTES and Remember NOT TO CHANGE YOUR EMBOUCHURE.
Normally it's just a matter of time and practice.
Good luck!
PS: I don't think it's your clarinet, like Lera said. Buzzing sounds and notes that don't come out (because of leaks) are mostly only with the notes that lay on the lower joint of the clarinet. And if you can play all the other notes on the reed that you're using, that can be the whole problem eather.
i guesse i didnt say it right... i cant play the notes from high f to high c with out buzzing. and istarted playing the bass clarinet at the beggining of sixth grade.
how long have you played the clairnet though? could be the bass is different enough, just keep working on it, usually buzzing is because there isnt enough air going through, or your emboucher isnt tight enough
