Abstract: A perforating gun train for perforating two or more zones of interest includes two or more gun sets made up of guns, detonators, and other associated equipment. In one embodiment, the gun sets are connected with connectors that can convey activation signals between the gun sets. The firing of a gun set creates this conveyed activation signal either directly or indirectly. In one arrangement, a surface signal initiates the firing of a first gun set while subsequent firings are initiated by firing of the gun sets making up the gun train. An exemplary connector is at least temporarily filled with signal conveyance medium adapted to transmit activation signals between the gun sets. In one embodiment, the signal conveyance medium is a liquid. The liquid can be added to the connector either at the surface or while in the wellbore.