Vapros, we need more info from you to help from a far for there are so many factors involved in pocketing balls. For instance; how are you addressing the shot, do you stay down on the shot, how true is your stroke, how strong is your focus, what's going through your head prior to missing a shot, do you have a problem with anxiety, how many strokes do you take before you fire, are you over thinking the shot, do you consistently stroke the same, have you tried various shot making systems, are you having a hard time knowing where to hit the ball, does playing position create problems, are you confused as to why you missed the shot, and do you consistently miss the same shot the same way, do you always use english on shots, or can you make balls with no english, why do you think you miss the shot?
All of the above can be improved upon, but first you have to realize that you need improvement in a certain discipline, and many players do not realize this. A good instructor should be able to pick up on any dysfunctional pocketing disciplines, and thus raise your game up substantially. But you will have to work on it, and may need to take refresher instructions to stay on track. Whitey