Animation clip 'walking' is not retargetable ...

I have more than one walking animation in my project. While uprading to Unity 4.3 i get this curious warning:

A click at the warning does nothing. The walking animations are fine from what i can see. So i have no clue which walking animation is meant.

How do i find out which animation clip is meant? What does this warning mean? What muscle definition?

Are you still looking for the answer to your problem lol