Hello, I have had a Audio Unlimited system with

Hello, I have had a Audio Unlimited system with two speakers for a few years, I liked it so much I bought two more speakers about two years ago. Again I wanted two more speakers, for a total of six, so I bought another complete system but the speakers on the new system did not work with the wireless control(s), the volume works fine using the manual + and - volume controls. I found that waving my hand in front of the receiving window on the new speakers while pressing the volume control on the remote unit activated the speaker volume. Frustrated with having to return and probably pay for return shipping I thought of taping a penny in the middle of the IRF(?) window of each speaker, now they seem to work just fine when using the remote for adjusting the volume.

Any idea on why this penny trick works? and should I be concerned the speakers will fail?

Thanks for any help,

Stan