This paper considers the impact of incomplete information on incentives for node cooperation in parallel relay networks with one source node, one destination node, and multiple relay nodes. All nodes are selfish and strategic, interested in maximizing their own profit instead of the social welfare. The paper considers the practical situation where the channel state on any given relay path is not observable to the source or to the other relays. Different bargaining relationships between the source and the relays are considered, and a framework for studying the efficiency loss induced by incomplete information is proposed. The source of the efficiency loss is analyzed, and the amount of inefficiency which results is quantified.