Build AssetBundle, missing shader.

My uniy version is 4.1.2f1.

Every asset file packing to a single little AssetBundle, and my building asset bundle process is as follow.

Build all textures, shaders, materials, fbx asset bundle.
    Build all prefabs asset bundle.
        Build all scene asset bundle.

When load scene, Most of the models correctly display, but some model missing Unlit Texuture shader.
By carefully view the log, I’m sure that I load the assetbundle in the correct order.

The strange thing is, I change the shader to diffuse, and rebuild all resources, they are all correctly display.

I don’t know why, please help, thanks.

Edit->Project Settings->Graphics, you could add your shader to ‘Always Included Shaders’, and rebuild your assetbundles