The two key feedback loops to follow are as follows:
1. Is the ball spinning properly? Yes/ No
If the answer is no, then your racket face will be too open. Make sure when you make contact with the ball the racket face is parallel to the TopspinPro screen.
If the ball is spinning, chances are you’re using the correct technique as it is really hard to make it spin the wrong way but just to make sure, it’s worth checking the second question too.
2. Did I manage this without hitting/touching the screens? Yes/ No
If you made it spin but your racket hit the top screen, you are wrapping your racket over the ball. This is a common misconception when trying to generate topspin. It causes inconsistent results because the racket face angle is constantly changing. Keeping the face constant at around 80 degrees will create a much more reliable topspin groundstroke.