solve error too high. Due to perspective set

I have been diving into some online tuts about animation but some things I dont get.

I use blender 2.68 and while setting marks I chose the option Perspective. All the marks I made in the video (a smartphone video converted from gp to mpeg) are set this way but after calculating i got a solve error of 9 and later even higher 11 or so.

I dont understand why I got a bad solver error. My goal is to make a video with a lot of perspective, so the object I will read into the movie should actually be big in front and then fade into the distance.

Any idea what the best solution is?