Blender FBX Animations import, nullreference errors, and copying from existing avatars

Okay, what i have so far. I made my character, and some animations for him, in blender. Exported as fbx, imported to unity, everything works fine.

Now what i’m trying to do, is to import some additional animations for him. I use the same armature, the same export settings, etc. Create the fbx, and import it;
For the Avatar of the new import, i select Copy from existing, and select the original character’s avatar, pretty sure that’s the correct thing to do

But it’s failing horribly. Any animations i import on the second round of importing do not play properly on the original character. He teleports to 0,0,0. Even reimporting animations i already made and imported successfully the first time around. I can repeat this entire process quite reliably. Importing an animated character that works fine, and then importing new animations and copying the avatar, which does not work.

Now in addition, and i’m VERY sure are related, ive started getting a few nullreference errors on entering play mode, while attempting to do this importing. They don’t reference any of my own code though, as far as i can see.

The first one is:

And the second, almost identical except the last two lines:

At the moment i’m still at the proof of concept stage with this. I need to figure out the workflow for importing new animations, without reimporting EVERYTHING, before i go any farther into making lots of anims.

any ideas what might be wrong. ?

I just had the same error message as your first one. I’m using Unity 4.5.5, using fbx imports from Maya. The problem went away after restarting the Unity Editor.