I am laying out a new design with PCB123 V5.5. When I try to connect a Top Trace to a Bottom Trace with a Via, I get 2 different Net numbers, and Trace to Trace errors.

How can I merge the 2 nets into one and eliminate those errors.

Why do some traces disappear when I close PCB123?
I finish my design, and save it, but when I open it again, some work has disappeared.

I am trying to add a Digikey 7 Segment DIP Numeric Display to my library, so I can use it in my design.

How can I add a Digikey part to my library?

I have run autoroute on my design. I get a message that there are 2 errors.
How can I find where those errors occur in the design?
How can I print the netlist?