Rates not picking up.

Rates available in system.
unable to query from rate enquiry.
When SAW triggered t osystem , unable to assign rates using assign rates action of agent.
when manually performed action assign rates, getting assigned
rates frm country to region, lane exists in rate service.distances calculated by extenal engine pc-miler.

wha can be the reason for rates not getting assigned with agent action assign rates, but gettng assigned if same action performed manually by user.