Be sure to use ALL the parts!
If the new TV you purchased doesn't put out any sound, make sure that the detachable speakers are ATTACHED and not on the coffee table. Don't let the professional installers leave while there are still parts are not attached to the TV that came in the box with the TV.
The sad thing is that neither the professional installers nor the manufacturer's tech support phone jockey realized that the detachable speaker wasn't attached.
Le sigh. At least it's all taken care of and working now.