Magnetism

I'm having some problems finding an expression to the magnetic moment of a rotating sphere of m mass with a uniformly charged surface and an angular speed w, the rotation axis is z through the center. It's supposed to be (5Q/6m)*L, where L is the angular momentum (mwr^2).
The integrals just won't lead me to it, I must be missing something crucial. So I would like some guidance on how to solve it, since this is pretty much freaking me out.

>>9
Fuck no, the Jacobian is (R^2)*Sin[@], so dA really is 2pi*R^2*Sin[@]*d@, Integrating dI*a gives (Q/3m)*L.