Bird wing animation flaps in opposite direction???

Hello I stumbled upon a weird issue:

I got an animated bird which flaps its wings upwards - and in the animation preview in Unity it plays correctly - but when I play the animation in the game the wing flaps downwards. Anyone else encountered this issue... and know what#s the reason for it?

Edit: found that it happens when using as an additive animation. It plays correctly in a blending loop though...???

 

Is the wing bone rolled around its local Y axis?

 

I thought of that too. No, it isn't.

Meanwhile I eventually got a clue, which is I maybe do not execute animations correctly.
So the wing starts from an upper position and then going downward, while the idle loop is the wing in a horizontal position. When I use the wing as additive animation it starts by going downward from the horizontal position instead of the upper position. In fact it never goes to the upper position at all, it's like he takes the horizontal position as the origin.

 

For the record, the reason is this http://answers.unity3d.com/questions/218370/basic-question-about-additive-animation.html
meaning that the additive animation is handled as a "change" but not at a fixed position.