Some animation can't use with other avatar except it avatar

I try to do aim system so I import animation idle aim to Blender then I rotate spline to make Aim up and Aim down and export it. I back to Unity and make Avatar mask (select just spline). If I change my character avatar to Aim up avatar, it work but when I change back to T-pose avatar it didn't work. I need to know why animation can't use with some Avatar. I export from blender in fbx.

ps. All of my animation is generic