Which box do you have?
do these steps
1. Turn on your STB.
2. Press reset key for 10 seconds and release.
3. After release a message will flashon TV "Force RF4CE reset. Box will reboot. Pair your RCU after rebooting"
And stb will automatically reboot.
4. Now when the home Channel appears do as I've told you above. i.e press * key for 5 seconds and then press OK key.
5 A screen will appear to enter code. Type that code
Pairing successful message will appear.