In other words, Program Change won't work the way you expect, because you'd be asking the program to load a big group of samples in a split second - and that can't be done. See? The old hardware synth change happened instantaneously - but sample based instruments take some time to load. Notation already has the instruments loaded, and the Program Change in that case is simply switching to a different instrument slot and different MIDI channel. But in Sonar - as I've explained, things are very different.