Editor script for editing animation settings after import?

I have been coming back to this problem every so often after Unity 4 was released. I am trying write a tool to quickly change the animation settings on a bunch of humanoid animations after they already have been imported so I do not have to manually change it per file, which is a really slow and tediously annoying process. Here is a snippett of code I am using.

 ModelImporter modelImporter = AssetImporter.GetAtPath(fileLocation) as ModelImporter; 
 ModelImporterClipAnimation _animationClip = new ModelImporterClipAnimation();
 ModelImporterClipAnimation[] _oldAnimationClip = modelImporter.clipAnimations;
 _animationClip.firstFrame = _oldAnimationClip[0].firstFrame;
 _animationClip.lastFrame = _oldAnimationClip[0].lastFrame;
 _animationClip.name = _oldAnimationClip[0].name;
 _animationClip.takeName = _oldAnimationClip[0].takeName;
 _animationClip.keepOriginalOrientation = true;
 _animationClip.keepAdditionalBonesAnimation = true;
 _animationClip.keepOriginalPositionY = true;
 _animationClip.lockRootHeightY = true;
 _animationClip.lockRootRotation = true;
 ModelImporterClipAnimation[] _clipAnimations = new ModelImporterClipAnimation[1];
 _clipAnimations[0] = _animationClip;
 modelImporter.clipAnimations = _clipAnimations;

Once in a while it will actually capture the old animation information I need but most of the time this line: ModelImporterClipAnimation[] _oldAnimationClip = modelImporter.clipAnimations;

returns null and I am trying to figure out why and haven't figured anything out.

Sidenote:

fileLocation comes from a selection of files I want to edit.