TextureImporter problem,can't preview high verion psd

hello,I have encountered a question in Unity ,when I tryed to write a TextureImporter class,here is a wrong: NullReferenceException UnityEditor.TextureImporterInspector.ApplySettingsToTexture () (at C:/buildslave/unity/build/Editor/Mono/ImportSettings/TextureImporterInspector.cs:1525) UnityEditor.TextureImporterInspector.ResetValues () (at C:/buildslave/unity/build/Editor/Mono/ImportSettings/TextureImporterInspector.cs:2339) UnityEditor.AssetImporterInspector.ApplyRevertGUI () (at C:/buildslave/unity/build/Editor/Mono/ImportSettings/AssetImporterInspector.cs:236) UnityEditor.TextureImporterInspector.OnInspectorGUI () (at C:/buildslave/unity/build/Editor/Mono/ImportSettings/TextureImporterInspector.cs:1420) PsdLayoutTool.PsdInspector.OnInspectorGUI () (at Assets/Editor/PsdLayoutTool/PsdInspector.cs:147) UnityEditor.InspectorWindow.DrawEditor (UnityEditor.Editor editor, Int32 editorIndex, Boolean rebuildOptimizedGUIBlock, System.Boolean& showImportedObjectBarNext, UnityEngine.Rect& importedObjectBarRect) (at C:/buildslave/unity/build/Editor/Mono/Inspector/InspectorWindow.cs:1231) UnityEditor.DockArea:OnGUI()

besides,Unity can't preview high version .psd file, like psd edited by pscc2015