Unity5 打assetbundle时，无法打成图集仍然是散图的原因

 1          2         string[] sprites = new string[]{ 
 3             "Assets/atlas/textures/t1.png",
 4             "Assets/atlas/textures/t2.png",
 5             "Assets/atlas/textures/t3.png",
 6         };
 7 
 8         string ab_atlas1 = "ab_atlas1";
 9 
10         for (int i = 0; i < sprites.Length; i++)
11         {
12             TextureImporter textureImporter1 = AssetImporter.GetAtPath (sprites [i]) as TextureImporter;  
13             textureImporter1.textureType = TextureImporterType.Sprite;
14             textureImporter1.spritePackingTag = ab_atlas1;
15             textureImporter1.spriteImportMode = SpriteImportMode.Single;
16             textureImporter1.SaveAndReimport ();
17         }