In FL Studio 5/6, I can't seem to get the CC17 vibrato control to work, and since FL Studio only allows you to assign controllers up to CC127, I don't know how I'll be able to access the other 131 vibrato control.
Basically I'm setting it up the same way that was described in the "Using GPO with FL Studio" tutorial, but putting CC17 on one of the knobs on the MIDI Out channels, but that knob has no effect. I do have the latest GPO update and have tried the controllers on both NV and V Flutes.
cc131 only applies to M-Audio keyboards. Actually, in M-Audio keyboards choosing cc131 sends Aftertouch data. For everyone else it is Aftertouch, sometimes called "Channel pressure." Vibrato intensity is controlled with Aftertouch and speed is controlled with cc17. If you don't apply Aftertouch you won't hear any vibrato. If your keyboard doesn't support Aftertouch then you will need to draw the data into your tracks.
P.S. Vibrato control is only available on NV instruments.