Belated tip as so busy!
If you don’t get what you wanted from you horse ask yourself this:
Did you ask the right question?
Did you ask the right question and in the right way?
If the answer is yes to both, then:
Does your horse know the question?
Does he know the answer?
Between these four questions you’ll find your problem. The first two are rider based errors and the second two imply that the horse does not know what you are asking, even if you are doing so perfectly!
Don’t get frustrated, just make sure the question is asked correctly, and the horse knows the answer!