Some theory, when you are dealing with one remote, then a 10% range of operation means that if I am only 9% high then it will work. If I learn this, and then the remote that I use to learn it is 6% high, then both devices are individually in spec, however the signal that I am producing is now 14% high. Now, if the receiver is 4% low then you have a condition where the learned signal will not work with the receiver but will work with the original remote. There are many variations on this scenario. And the best way to resolve it is to plant yourself in front of the device and using the test button in the pronto editor add IR, adjust the base frequency up and then down until it doesn't work. And then set the value to the split difference to the two. This will essentially calibrate the Added IR to the center operation frequency of the receiver, irrespective of the original transmitters frequency.