I worked out my problem. I was looking in the wrong place.
I originally set up the comet orbit in my Starry Night program, early last year just after discovery, by entering those first derived Besselian Orbital elements. I checked the Besselian elements today. The elements have been refined and updated at the Harvard minor planet centre and mine were now different enough that the old elements are showing the comet at the wrong position. I'll get it next time. So it wasn't in the expected position with respect to the field stars. When the Moon relents a bit.
I realised when I saw a photo online taken at the same time I was observing and the comet appeared to be in the wrong place relative to the field stars.
cheers
Joe