Sorry, but I don't understand what you are trying to do here. Maybe you could explain more? Tell us what is the result you want, so we can check what's going on.
If you are trying to create a midi-sustain app, its not like that, from what I see. You need a list of all on-hold notes, and release one-by-one when you hit release. Unless I'm getting things all wrong... 
Wk