So, I just got my 3x3x3 Cube, I really wanted to solve it, so I was very committed. I read the complete guide, I looked up a few guides on the Internet too. So, I memorized all the algorithms fairly quickly, and I know when and how to perform them. So, when I get to the last cube that I need to put in place using the Ri Di R D algorithm, as soon I finish doing it twice, the cube isn't solved. Only the second layer, with the exception of one cube is solved, so it's like I went 3 steps backward instead of finishing it. I'm really frustrated, and have followed every guide to a Tee. I have no clue what I am doing wrong, and the same situation arises almost every time I try and solve the cube, it has only not happened twice, out of the 50 or so times. I really need help, and any input is appreciated!