Lines disappearing when saving as jpeg

[One Fun Nana]

I am trying to trace over some lines that are too light on my image to make them darker.  When I save the image as a jpeg, the lines disappear.  Any suggestions?

[Norman Sanders]

If you traced over them on a separate layer, the file was flattened when you saved as Jpg. The work on the separate layer is incorporated into the jpg image.

[One Fun Nana]

I'm still struggling to get this figured out.