We are trying to get a Zenith plasma TV, model Z50PV220, working with a soundbar. First I bought a Vizio soundbar and connected using the digital optical port. The soundbar seemed unable to find the signal, and then all of a sudden it did and sounded great. A few minutes later we changed from Roku to direct TV signal and the soundbar stopped working. We could not get it working again using Roku or not. Today we hooked up a Megacra soundbar via the digital optical connections and we can't get any sound out of the soundbar. However, if we adjust the volume on the soundbar using the remote there is a scratchy clicking noise which becomes louder as we increase the volume. This sound does not occur if we adjust the volunme directly on the soundbar. Don't know if this is a clue. Can anyone help, please?