Triangle Structure face culling

I tried making a comp where the user clicks three points and they are stored in a structure and then a simple triangle is rendered by the triangle structure renderer. But it doesn't behave the way that I thought, please take a look. It's like it always expects the vertices to be listed in a certain direction, otherwise it culls the whole triangle face. I am sample and holding the xy positions of the mouse (in the attached comp the z=0 but i've tried it with a floating z) in three points, one for each mouse click, then struct maker into the renderer. But the last vertex always seems to only want to complete the triangle on a single side..easier to have a look than explain, is it a quirk of the renderer or am i doing something wrong?