If a cone with perpendicular height of 6h and radius 2h has the same volume as a sphere of radius r, show that r= cuberoot 6h.

I got:

1/3 pi r squared x h = 4/3 pi x r cubed substitute

1/3 pi (6h) squared = 4/3 pi x r cubed divide by 3

pi (2h) squared x 6h = 4 pi r cubed divide by pi

(2h) squared x 6h = 4 r cubed

24h cubed = 4r cubed

...where am i going wrong?