issue tracking sequence I am new to blender, I recently started to learn VFX.

I get an issue with tracking. I keep getting those 2 errors :
- Failed to solve the motion: most likely there are no good keyframes

And

At least 8 common tracks on both keyframes are needed for reconstruction


I tried with many different video sequences, tried manually add tracker, detect trackers automatically, I even tried with one sequences that had tons of trackers but still the same error.
Could you give me a hand?


Another image


This seems a lot of trackers but i tried it to see what was up, usually I only add like 20 trackers
Try to cleanup your tracks with different error threshold from high to low. You have too many unnecessary tracking points. You need at least 8 good trackers, but having way too many might make the process less accurate. See: 
How can I get better results when doing camera motion tracking?

Then if Keyframe checked option won't work correctly, try to set the best key range!