Hi George,
Your plot includes the sky background (from air glow, light pollution and from M31) which dominates the spectrum. The strong emission lines are airglow and light pollution. To see the target spectrum you need to just select the target spectrum (the narrow band) subtracting the background first. If you look at my sky background subtracted and wavelength calibrated spectrum you can see there is no emission line, including at H alpha (6563A) currently.
Cheers
Robin