Draw a line and make a bullet follow it

I would like to make a game where I can draw a line by clicking and dragging the mouse. I would then like a bullet or sprite follow the line. When it gets to the end of the line it should just carry on in the direction it was going.

I have tried the example on this post:

scirra.com/forum/how-to-make-bullet-follow-the-line-just-drew_topic53718.html

But I get the same issue with all of them that it seems erratic in the way it creates line segments. It will always create what seems like multiple lines and lines going off from the original line making the rocket go back and forth etc

I'm new to this software but have a few years development experience but could really do with some help here

Thank you