The revive goal has higher priority than delivering medpacks. There are often other players in your team who need help too. There's also a distance limit and medics can't hear you if you are too far away. So the medic can't respond to your request every time. But he should come to you if he is near you and does not have any more important goal.
thanks for responding.
on my setup, they never deliver medpacks, regardless of how close you are when requesting "medic". i have been standing right in front of a medic almost dead, and the bot will not give a medpack to me after requesting "medic".
the LTs however, will always give out ammo when asked.
just kind of frustrating.