Path tool deactivated with 'no smoking' symbol.

[Mugunga]

All I'm trying to do is draw a dotted line with the path tool. However, when I have the path tool open, it doesn't create paths when I click. there is a little symbol above the path tool that resembles the 'no smoking' frame (without a cigarette), which seems to mean it isn't active. I did Select -> None, and I have no floating layers. How do I make my paths work again?

Thanks.