Where is the RF antenna located on the HR24 motherboard? It sometimes fails to respond to commands. When I get no response, I look at the light in front of the HR24 and see it not blinking when pressing a button on the remote. I see the light on the remote when I press a button. When I move the remote around, it finally responds. Never had this problem before with the HR21 it replaced. Is it possible there is interference of some sort? Thought RF has no "dead spots". Is it an HR24 issue?