Trade Port Routes Question
Okay. I have been trying to maximize my profits with having the longest trade route possible and for a while I thought I had one that was pretty good. Much to my surprise that after I colonized a dead asteroid, the trade lane split in half almost.
I thought I understood how the trade port routes worked, but I'm not sure anymore. I've looked up posts on the forums and on a solar wiki site, but I already knew what they told me.
Picture: 
The yellow circles are planets with trade ports. The red X's are planets that do not have any trade ports. The brown lines were where my trade lines were before I colonized that dead asteroid in the lower right corner on the picture. And I'm not sure if colonizing the dead asteroid exactly caused this, but I did remember that before I had colonized it that the trade route was longer and more profitable.
Is this a bug, or is there something I'm not understanding about trade lanes?