Dynamic SkinnedMeshRenderer doesn't animate

I have 2 similar prefabs with only different clothes (list of SkinnedMeshRenderer) which are included in **Mesh** Object. All SkinnedMeshRenderer has **no Root Bone**, only Mesh and Materials are specified.
The 1st prefab looks like this:


Then I copy the other clothes(also Mesh Object) from 2nd prefab to 1st prefab and hide the old clothes.
However, when I play scene, it display like this:



As you're seeing, the clothes isn't attaching to character, even I play animation, it also doesn't work.
I tried a lot of ways but couldn't figure out what is wrong here. Please help me.

PS: I tried to post this question to http://answers.unity.com, but Captcha didn't work and I couldn't submit it.