I have an A-300 PRO and was using Halion Sonic SE, when I needed to get more range on the keyboard. So I plugged my FATAR Studio 900 into the midi in port on the A-300 Pro and began having lots of fun. Then as my melody was reaching its climax the all important A key made hardly any sound at all. At first I thought that the key had broken (it is old) so I switched on a hardware synth to see if I got the same problem from the FATAR to that, I didn't. So then I selected the right octave on the A-300 to see if it might be something to do with the set up on Halion, midi messages, activation keys....... But the A-300 played the note fine also.
If anyone can make any sense out of what is going on here, I would be grateful.