Because the indefinite integral of the electric field results in a negative value? (As the function is proportional to $r^{-2}$?
I've got to be missing something... Help please!! Thanks!
Also, I took the integral from infinity to the radius of the charged sphere and got
$$V = \int_\infty^R{\frac{q*dr}{4*\pi*\epsilon_0*r^2}} = -\frac{q}{4*\pi*\epsilon_0*R}$$