Basic pen tool line

[ProfessorB]

When I draw a line using the Pen tool I can't maintain it on the screen, because any action I have tried deletes the line. I have scoured forums and videos but apparently this is not a major problem for most. However, I have spent well over an hour just trying to solve this simple problem which should be extremely intuitive since it is the second most simple act one can perform, a point being (possibly) simpler. This is very frustrating because it is apparently TOO simple to include in any discussion or video I have yet encountered. It is astonishing to me that such a simple and basic task such as drawing a straight, horizontal line can have such a non-intuitive component as how to release it. I have used many vector drawing programs in the 37 years I have been computing and have never encountered such a frustrating process  to simply draw a straight line. Can anyone please inform me of the solution to this issue? Thanks...

[R C-R]

I'm just guessing, but is it possible you are drawing on a white background, the pen tool's fill color is set to white, & the stroke is set to none; or possibly some other variation of fill/stroke settings that would make the shape invisible?

 

Try this: Select the pen tool, set it to polygon mode, & click successively on three points not all in a straight line on a new, blank canvas. On the layers panel, you should see a new layer named "(Curve)." Select that layer with the mouse pointer. In the contextual toolbar or on the Color & Stroke panels, set this layer's fill to (for example) a bright red & its stroke to 5 pixel wide black. Switch to some other tool. Is the line still visible now?