Okay so i have pokemon Platinum and Dialga and Palkia Wont Come Out?

Okay so i have ped the pokemon league twice (Normal lvs. and then the second set of Lvs.) and i have the national dex from oak and stuff i found the orbs and everything so why wont freaking dialga and palkia show up its really ticking me of and frustrating me please help me!!!! and dont answer with i dunno cuz a lot of ppl do that just to get points on here and its also annoying grrrrrr!!!!!!!!!!!!!!