Question: Integrating an analytic solution

Hi,

I have a question about integrating an analytic solution to a differential equation in Maple. I have solved a system of 3 odes:
sol := dsolve({initial, syst}, func, numeric)
where
syst := diff(OmegaLambda(x), x) = ode1, diff(OmegaK(x), x) = ode2, diff(lnH(x), x) = ode3.

This then gives me analytic solutions as a function of x to the 3 odes and I can plot, say the third solution, by defining
lnH2 := x-> rhs(op(4, sol(x)))
and plotting lnH2.

Now I want to integrate something that is a function of lnH2 with respect to x. However, I'm not sure how to do that. It doesn't seem to recognize that it is a function of x when doing:
int(exp(lnH2), x = 0 .. p).
It just thinks that exp(lnH2) is a constant.

Does anyone know what the syntax is for integrating an analytic solution??
Thanks!