the 'calculate shipping' function does not work with the geoshipping module. with geoshipping, the customer only sees the shipping costs once they've proceeded to the 'review order' step in the checkout process.
however, never fear! arbel has been doing a lot of work improving the geoshipping module, and his new module 'world quotes' does give the customer a preview of shipping costs earlier in the process:
check it out and help with testing. world quotes has mo' better features than geoshipping, so will probably eventually supercede it.