Just to be absolutely sure:
Check the wiring to make sure that pin 1 on one connector goes to pin 1 on the other. When held flat and stretched out, the modular connectors on each end of the cable will be oppositely oriented from each other.
See the diagrams in the Cable Assembly sections of the Jaguar (or Black Jaguar) getting started guides at
www.luminarymicro.com/jaguar
Sorry to repeat what others have suggested, but I have seen weird errors when a perfectly crimped cable actually crosses the signals.
-David