# Instantons in type IIA theory and correlators

Hi,
in type IIA theory it is possible to compute correlation functions by infinite sums over instanton areas $$\sum e^{-Area}$$. Wouldn't that mean that it is possible to get two-point correlators? Imagine a torus with one brane on each of the two lattice vectors. They bound a parallelogram which is identical to the torus covering space. Is there anything that prevents us from summing up these areas to a valid correlator coming from just two branes?
Thank you,
hines