Accuracy

If you have the same problem @nGord has, I suggest you take a full look at the options there are and how you got to the point where the bot is about to hit the ball.

If you are still stuck, the read the following spoiler.

Spoiler: How to get the ball to touch the exit

Remember the moving block you moved in the beginning to free our favourite bot? Well, you need to place that block right in the space where the ball is going to roll once the bot hits it.

how to let the ball fall?

@linzunhui you have to place B right in front of the ball then step backwards till the edge of the platform and then place B right in front of the ball again. This will make B move the ball.