Thanks djy, that would be great and most appreciated.

The appropriate code is selected in the RM-991 via 1 of 3 methods, A: in which you enter the code, B: in which you search the code manually (the controlled device reacts with volume-up when you get the right code) and C: In which the RM-991 automatically cycles through all the codes (the controlled device turns off when it hits the right code). I've confirmed that these 3 methods do work on the TV, which is one of the things I can control, but not on set-top box, DVD or amplifier, so I think it's a case of the RM-991 just not knowing the code.

In this case, the only recourse is learning, which I am not able to get the RM-991 to do. Hope you can shed some light on that.
Thanks!