I put NGUI folder to Plugins, editor error happens. (NGUITransformInspector couldn't)

Unity Engine
1

Error message is

“Instance of NGUITransformInspector couldn’t be created.
The script class needs to derive from ScriptableObject and be placed in the Assets/Editor folder.”

  1. NGUI import
  2. make Plugins folder
  3. put NGUI/ to Plugins/
  4. select object (ex. Main Camera) → Error happens

How do I get rid of the errror?

2

I solved.

I chenged directory like this.

http://d.hatena.ne.jp/shinriyo/20120606/p2
(japanese)