Im at the part when you put the sun and moon stone in.They are now in but i have tried many many times but i cant seem to hti the two blue blocks at the same time i have tried :use Koops's shell by pressing "X", so place Koops in his shell state by
pressing and then holding X next to the platform with the Save Point and
keep him there. Now, with Koops right there (make sure he is lining up
with the blue "!" block on the left side), go (with Mario) to the right
blue "!" block on the right side and jump on it and immediately let go
of X and you should hit them both simultaneously. If you fail, keep
trying like I told you and you'll get it. Once you get it, the pillar
in the middle will collapse, revealing a pipe.

That cheat but its not working i have done it over and over again.Help!