How do you get the Suite Key in Pokemon Diamond and Pearl?

When its raining at the hotel's area stand outside the hotel's entrance and use the item finder app until you find it the suite key. When you give it to the lady she only gives a stupid lava cookie!When its raining at the hotel's area stand outside the hotel's entrance and use the item finder app until you find it the suite key. When you give it to the lady she only gives a stupid lava cookie!When its raining at the hotel's area stand outside the hotel's entrance and use the item finder app until you find it the suite key. When you give it to the lady she only gives a stupid lava cookie!When its raining at the hotel's area stand outside the hotel's entrance and use the item finder app until you find it the suite key. When you give it to the lady she only gives a stupid lava cookie!