Help 'spaw, Bill Day, et al.

I made the autoharp gizmo without success: Clipped a plug off one end of a 12" patch cord (guitar) and put an alligator clip on the exposed copper wire, with good connection I think. I plugged this gizmo into the input jack on my Korg tuner and put the alligator clip on tuning peg(s) of the autoharp. No signal, no response. What could be wrong?

Thanks Fortunato