Thanks DJY for your effort in this. And no offense taken, in fact I am seeking help on this forum because I think I might be doing something wrong and hope someone (like you) can show me what it is.
Your instructions are identical to the instructions in the manual of the RM991. I've followed them through before and I tried it again after reading your message, but still no luck for me with my starhub set-top box.
I thought that perhaps the transmission from the original remote to the RM-991 might have been a little iffy, so I tried it 3 or 4 times at slightly different distance between the remotes during training. In all cases, the RM-991 behaves as you say during the training ("IR-in", press key on original remote, "key-in", press key on RM-991...repeat...) , but after programming, when I try to get the RM-991 to control the set-top box, it does not turn on. The set-top box does react to the RM-991's signal though: A green light on the set-top flashes while I am trying to to turn on with the 991, but after I release the on/off button (on the 991) the green light stops flashing and the set-top remains off. Using the original remote, that green light flashes, but the then the set-top actually turns on.
The IR-light coming from the remotes is detectable by a digital camera (or handphone). I've used my HP to look at the signals coming out of both the 991 and the original remote next to each other. I can see the IR-LED's in both RC's flashing. I notice the 991 has two IR-LED's while the original only has one. I don't think that should be the reason though. They are flashing pretty fast, but my impression is that the 2 sequences of flashes from the 2 RC's are not the same, which would also explain why the 991 is not turning on set-top. *sigh*. not sure what to do now.