Hi Murray,
To add my 2 cents worth.
I am relatively new too, and I dont have the Nexstar but I do have a goto.
When setting the date and time, you usually have to specify the time zone.
Even though you have told it already the Longitutde and Latitude.
But on one of mine, I found setting to what I sthought was Eastern Standard Time actually was some Amreican time zone.
So I had to use GMT after converting Sydney time to GMT. (ie subtracting 10 hours).
I just thought that this may be something to do with your problem.
Anyway, cheers and good luck
Allan