In general, you don't need to connect your base stations to each other with the sync cable. However, if you have a hanging object from the ceiling that is above the play area or if your base stations need to be positioned low such that your head or hands block the bases from seeing one another, this may affect the syncing of the base stations. You'll need to attach the sync cable.
Attach the sync cable to both base stations and make sure to route the cable outside of your play area.
Press the Channel buttons on the back of the base stations so that one base station is set to channel "A" and the other is set to channel "b".
sync cable doesn't work for me. one base station periodically just stops tracking... this base station does not like the latest firmeare update so its on an older version while the other base station took the update and works fine. I am told that the next firmware update should work.