How do you unlock mystery gift in Japanese Pokemon diamond or Pokemon pearl?

Go to Jubilife City. Then enter the Fun and Games TV Station. Climb to the third floor. In the room, you'll notice a man and woman standing beside each other. Talk to them and the man will ask you a question. Answer "everyone happy" and "WIFI connection." He will say "very good" and give you the mystery gift. Save your game and turn the power off. When you repower go to the menu where you normally start the game. Click on the Mystery Gift button and you'll be there. The program does not give you a gift at first. But, it does give you the chance to get the member's card for Darkrai, the Azure Flute for Arceus, and Oak's Letter for Shaymen. Good Luck.