How do you use the dowsing machine in Pokemon platinum?

i can't really give you any good advice but i can tell you this.If you are looking for the suite key you exit the hotel and then you walk to your left till you hit a wall. Then after all that walk forwards twice. Then press the dowsing machine app and you will see a grey dot look in all 4 directions keep pressing on the app and the a button and you will obtain the suite key.