Blender to Mixamo to Unity: Animation Problem

Hi, I have made my own rigged character model in Blender. I put it into Mixamo and downloaded the animation and I tweaked the animation in Blender and all looks good. But when I import it into Unity the animation went wrong, the animation works but in the wrong way. Here are the pictures: 1. The posing and animation in blender:

1. and this is the animation in unity.

I have tried to redo the animation and add keyframe on every bone but it still doesn't work... Any help or advice would be appreciated! Thank you very much!