[Cannot see lines using line tool (shows up as dots)]

Hi,

 

I'm new to using paint.net, but I've searched the history of this forum and can't seem to find anyone with the same issue.

 

I simply drew a line as you normally would using the line tool, but its only showing up as a series of dots. I tried removing some layers but its the same thing with no layers.

 

Any help would be great!

 

Cheers