1997 Acura CL Unresponsive to both remote lock/unlock

We recently noticed that both of our remotes no longer activate (with a chirp) when we try to remotely lock or unlock the car. So we have to use the key to lock/unlock it. I suspect that due to its age some electrical component or fuse must be the source of this problem. I replaced one remote with a new battery and it still failed; the other remote is more rarely used and still failed.

I'd appreciate knowing what you think is the most likely cause of the problem, and if you believe if could be a simple electrical replacement issue.

This is the first time I've used your service and think it's a great idea. Thanks, Ron