Planet Studio

Is my planet studio broken or I didn't use it in the right way?I am MacOS and I'm tring to make my own system. I create my star and planets, and succeed change the defult star to my own. I clicked add child planet and I can find it in the planet icon on the left, but it is not on the map. I know I can edit planet by clicking them on the map, but it is not on the map that I can edit.