Determine the volum of a solid of revolution when the region bounded by $\displaystyle y = \sqrt{x}$ and the straight lines y = 2 and x = 0 are rotated around the line x = 4

my answer(which is wrong)

$\displaystyle V = 2\pi \int_{0}^{4} x ( 2 - \sqrt{x}) dx$

$\displaystyle V = 2\pi ( x^2 - \frac{2x^\frac{5}{2}}{5} )\big|_0^4$

$\displaystyle = \frac{32\pi}{5}$

??

what am I doing wrong?