Are you using an external sound module or the built in Mac sounds ?

Does the patch change to acoustic guitar if you change it during playback ?
If you are able to get the guitar sound during playback, make sure the next time you save your song to do "Save with patches" and select the "Acoustic Guitar" sound from the pop-up menu (for melody track) in the dialog, otherwise it may revert to vibraphone on the next launch.

If you're using an external sound module make sure you have "Program Changes" checked under the "Recording Filter" dialog under the MIDI menu.

Hopefully this helps.

- Jay

Last edited by JayO; 03/20/10 09:13 PM.
MacPro 5,1/12 core@3.46GHz -- OS X 10.15.7 -- ATI 7970 -- 32 Gig RAM -- Crucial 500GB OS SSD -- Samsung EVO 1TB Audio/Sample SSD -- BIAB 2024 -- Logic Pro X -- Cubase Elements 14 -- Too many plugins