How do you use the itemfinder in emerald?

After beating May on the way to Mauville City (which I think we all know is not the easiest part of the game), she gives you the itemfinder. It can help you locate what the game calls "invisible items", even though you can walk on the spot that they are on, so I guess they're buried or something. Usually, there will be a spot set apart from the ground around it where the item is, like a spot of short grass in the middle of a patch of tall grass. If you want to use the itemfinder, go to "BAG" in the menu (open the menu by pressing "START"), go to the "KEY ITEMS" pocket, and scroll down until you highlight "ITEMFINDER". Press the "A" button. Select "USE"*. The screen will go back to the field. You will hear three beeps, one loud, one soft, and one loud. You will then turn in the direction the item is in**. Work your way towards the item until you spin in a circle and the itemfinder shakes wildly. Step one place of the spot you spun on and click "A" facing the spot and you have found a hidden item!

*You will also have the option of registering the itemfinder, which means you can use it at any time by pressing "SELECT". However, I recommend registering your bike, or if you are fishing, your fishing rod once you obtian those items.

**If there is no item within the screen that you are standing in on the field, the itemfinder will not respond.