motion tracking

Hello i have a problem can anyone help me to solve this problem?:

i use v2.73 and i’m busy with motion tracking of a video, this is the problem that i have:

i have placed 8 or more markers in the video but if i press “solve camera motion” it say’s that i need to place a minimum of 8 markers in the video.
i did controll all frame’s but all have 8 or more what now?

do anyone how to solve this?

Ensure you have at least 8 common markers that are tracking between the two set keyframes.
Supply a example blend file

Richard Marklew is correct. You too keyframes must have 8 or more markers, plus some noticeable parallax to get a good 3D solve.