Hi, I'm 50 years old and have been playing the cornet for nearly 4 years (late starter). I play second cornet in a brass band and I feel I'm getting left behind by other beginners. I've had a lot of private lessons from a reputable teacher, I've got plenty of books ....ARBAN, CLARKES, HOW BRASS PLAYERS.... etc... I practice every evening for 45 mins to an hour and still I struggle to play higher than 'G'. In fact it all begins to sound after middle 'C'. I'm beginning to feel I reached a plateau around 18 months ago and I'll never really get much better. Any thoughts?