The missing jumper bar would explain the problem.
Just use a bit of the speaker cable you already have between the 2 sets of terminals. This can be done by cutting a small piece and connecting that way or you could do it by stripping more off the end so that it reaches through both terminals. There is no need to buy another bar or biwirable speaker cable.
Well that was simple and worked first time. Thank you very much for your help, PSM1. You have saved me hair, time and money.
Now to wait for an empty house so I can run Audessy and get the receiver to calibrate stuff.