Atlas maker error

[SanSolo]

I have read previous posts about fixing the error with Atlas maker in Unity. I followed the steps: set all textures to type advanced, unchecked generate mip maps, import type is lightmap.

But i keep getting this error when i try to create Atlas:

1. importer.GetNPOTScale() == TextureImporter::kNPOTKeep
2. UnityEditor.AssetDatabase:ImportAsset(String, ImportAssetOptions)
3. NGUIEditorTools:MakeTextureAnAtlas(String, Boolean, Boolean) (at Assets/NGUI/Scripts/Editor/NGUIEditorTools.cs:489)
4. NGUIEditorTools:ImportTexture(String, Boolean, Boolean, Boolean) (at Assets/NGUI/Scripts/Editor/NGUIEditorTools.cs:503)

[SanSolo]

Any help please.
Unity version is 4.6, NGUI 3.7

[ArenMook]

"import type is lightmap"? Eh? Import type should be automatic truecolor.