用NGUI生成图集报错

importer.GetNPOTScale() == TextureImporter::kNPOTKeep
UnityEditor.AssetDatabase:ImportAsset(String, ImportAssetOptions)
NGUIEditorTools:MakeTextureAnAtlas(String, Boolean, Boolean) (at Assets/NGUI/Scripts/Editor/NGUIEditorTools.cs:487)
NGUIEditorTools:ImportTexture(String, Boolean, Boolean, Boolean) (at Assets/NGUI/Scripts/Editor/NGUIEditorTools.cs:501)
UIAtlasMaker:UpdateTexture(UIAtlas, List`1) (at Assets/NGUI/Scripts/Editor/UIAtlasMaker.cs:493)
UIAtlasMaker:UpdateAtlas(UIAtlas, List`1) (at Assets/NGUI/Scripts/Editor/UIAtlasMaker.cs:575)
UIAtlasMaker:UpdateAtlas(List`1, Boolean) (at Assets/NGUI/Scripts/Editor/UIAtlasMaker.cs:558)
UIAtlasMaker:OnGUI() (at Assets/NGUI/Scripts/Editor/UIAtlasMaker.cs:879)
UnityEditor.DockArea:OnGUI()