How do I place Peak Blocks in the Johto Safari Zone (Pokemon Heartgold)?

I have National Pokedex, have completed the first 2 challenges, and have been called and can place blocks. But the only blocks I can place are Shrubbery, White Flower, Red Flower (all Plains blocks), Lampost, Bench, Flag (all generic blocks). So I have no Peak, Forest, Grassland, or Waterside blocks to place. Is there a way to switch out objects or do I need to wait for another phone call?

Thanks in advance.