Finale 2010 Will Not Decrescendo On Single Whole Note? (Woodwinds)

Wftla;sdkfjaf?

So, I'm working on a new piece and I have a single measure, 4/4 time and three woodwinds (flute, oboe and B♭ clarinet) that have a whole note.

I just want them to gradually fade out and Finale apparently things that woodwind players can't change their dynamic range mid sustain?

Well I know what it is, it's trying to change key velocity which... isn't changing as it's a single note, rather than changing the volume or regular velocity.

I tried editing the MIDI data; I tried adding in hidden dynamic marks; I tried creating my own custom expressions... nothing has worked.

Any suggestions?