I've managed to learn this piece, and play it in its entirety by memory fairly well, but I still can't play the trill part towards the end. It's something like Ab and Bb with your fourth and fifth finger on your right hand. And then your thumb and index fingers on the D and Eb in the same octava. Anyone that has studied or played this piece will know what I'm referring to... I'm guessing my fingers just aren't strong enough? I usually do not play the D and Eb trill, and it still sounds decent, but I would like to play both trills, since both trills simultaneously creates a much more touching effect.
Are there any études that I can study perhaps that will help improve my trills in all fingers?
Sorry my english is not very good.