one mistake i made with nodes was pointed out to me by rharv. you can't just add a node or the volume will change gradually from the previous node. i wanted to mute a track for just two bars so entered a zero node and the program faded the volume from its previous set level over about thirty bars and introduced loads of cc7 changes in the event list.

the trick is to enter before and after nodes. a first node for the volume set most recently and then the new volume a little later. often you can see a 'gap' in the audio and if you zoom in you can place the 'after' node very close so you get an instant change - unless of course you want a gradual one. to get a fader move up do the reverse.