I have landed a rover alongside small relay on duna as part of an expedition. the rover has a communtron 16 and the relay has an RA-2. the relay connects to a spacecraft orbiting kerbol close to kerbin and then back to kerbin, meaning i can control the relay, but not send data because it has no non-relay antenna in range of a relay.
the rover has the small communtron 16, which is right next to the relay, yet cannot seem to connect to the relay in order to transmit its data.
idk why, as in my head the antenna should be able to connect to either the relay on the surface of duna with it, or one of the satellites in duna orbit.