Explicit solution could not be found. using solve command

b= solve ('(b^2 + a)^(3/2)*(2* b^3 - a^3 - 1) - b^3 - a^3*b^3 + 2* a^3=0','b')

Warning: Explicit solution could

not be found.

KINDLY HELP WHY I AM GETTING THIS ERROR

THANKS