Yes, I were thinking the same thing as BunnyVoid, you have the exactly the same problem that we discussed in Adams thread one or two days ago =)
Here is more visual reference,
I put square bits of paper in line like shown in the top picture. Then I sat down by the end of this line and took a photo from an angle very close to the floor. I used a 14 mm lens, and you can see some distortion on the square closest to the camera (because it's close enough to fall outside the cameras cone of "vision") but since the only way to avoid that distortion would have been to take a few steps back this would only mean that the same thing would apply to the first square as it does to the second in the photo.
Anyway, now that I've explained the experiment, let's make an observation. None of the angles in a direct line from the camera to the horizon are less than a 90 degree angle, not even the distorted one closest to the lens. If located on the horizon such angles would be 180 degrees. If an angle is less than 90 degrees that would then imply that 1. It represents an angle that is less than 90 degrees if viewed from above, or 2. It's drawn incorrect.
And that's why you need to space the vanishing points wider than you've done up until now =)