I'm fairly new to the Inkscape world but have wasted literally hours today trying to figure out what I'm doing wrong that I can't get the result I'm looking for. I'm creating a logo that requires two opposing 'curves' and was using the advice given here: https://www.youtube.com/watch?v=UjmER3xMC0o to create the effect I need. Unfortunately, every time I try to use the pen tool, I get one of these:
Help? My process has been:


In case it makes any difference, I'm working on a Mac via XQuartz 2.7.8.