
Check to see if your cm11a device is actually registered int he webadmin page.
From the left click 'Interfaces'
A new window should open up in the right. There you should see your cm11a listed, it should show that there is a com port for it, in the top drop down
Next click on the entry's 'Advanced' button. On the left of the new window that opens you should see 'Registered Yes'
That way you know for sure that the system knows it is there.
If any of these things are not so, unplug the cm11a from the wall receptacle and wait 30 seconds, and then plug it back in, then do a quick reload router.
I have attached some screen shots from mine below. I use Insteon and X10 devices in my house (more X10, as they work well and are easy on the wallet)
And I have all kinds of scenarios set up, and lots of buttons. You should need no special intervention. Provided the RCA device is compatible with the cm11a, and I am pretty sure it is, you should just be able to use it.
Also make sure the "Controlled by" device is the Core, not the Core/Hybrid, I made this mistake once.
Best Regards, and Best of Luck,
Seth