I am trying to have playback of a previously recorded acoustic guitar track routed into the AUX input on the Perform VG to use as basis for figuring the harmonies for the purpose of separating the vocals and guitar tracks in a recording but it’s not recognizing it. The harmonies are all random just like when you sing into the unit with no accompaniment at all. I see in the manual it says this is supposed to be possible. It says it can use either the guitar input, room sense or aux input so I’m wondering why I can’t get it to work. Thanks in advance for your help.