MirrorReflection script, adding image effects

Hi! I'm using the MirrorReflection4 script from the wiki in my game. ( http://wiki.unity3d.com/index.php/MirrorReflection4 )

It works great by default. I'm using the Edge Detection image effect on my game and wanted to add it to the reflection so it properly matches what you see in the world.

The way I did it was by adding this:

 using UnityStandardAssets.ImageEffects;

and then on the script where I found this line:

 reflectionCamera.gameObject.AddComponent<FlareLayer>();

I added this right below it:

 reflectionCamera.gameObject.AddComponent<EdgeDetection>();

Now here is the part I'm stuck on: this works great in editor, but in builds I get an error and the edge detection doesn't happen:

 NullReferenceException: Object reference not set to an instance of an object

This is the full error on the log:

 Missing shader in Mirror Refl Camera id24260 for 16178 (UnityStandardAssets.ImageEffects.EdgeDetection)
 UnityEngine.DebugLogHandler:Internal_Log(LogType, String, Object)
 UnityEngine.DebugLogHandler:LogFormat(LogType, Object, String, Object[])
 UnityEngine.Logger:Log(LogType, Object)
 UnityEngine.Debug:Log(Object)
 UnityStandardAssets.ImageEffects.PostEffectsBase:CheckShaderAndCreateMaterial(Shader, Material) (at D:\Unity\GAME\Assets\Standard Assets\Effects\ImageEffects\Scripts\PostEffectsBase.cs:21)
 UnityStandardAssets.ImageEffects.EdgeDetection:CheckResources() (at D:\Unity\GAME\Assets\Standard Assets\Effects\ImageEffects\Scripts\EdgeDetection.cs:39)
 UnityStandardAssets.ImageEffects.EdgeDetection:OnRenderImage(RenderTexture, RenderTexture) (at D:\Unity\GAME\Assets\Standard Assets\Effects\ImageEffects\Scripts\EdgeDetection.cs:72)
 UnityEngine.Camera:Render()
 MirrorReflection:OnWillRenderObject() (at D:\Unity\GAME\Assets\_ASSETS\mirror\MirrorReflection.cs:86)
  
 (Filename: D:/Unity/GAME/Assets/Standard Assets/Effects/ImageEffects/Scripts/PostEffectsBase.cs Line: 21)
 
 NullReferenceException: Object reference not set to an instance of an object
   at UnityStandardAssets.ImageEffects.EdgeDetection.OnRenderImage (UnityEngine.RenderTexture source, UnityEngine.RenderTexture destination) [0x00056] in D:\Unity\GAME\Assets\Standard Assets\Effects\ImageEffects\Scripts\EdgeDetection.cs:79 
 UnityEngine.Camera:Render()
 MirrorReflection:OnWillRenderObject() (at D:\Unity\GAME\Assets\_ASSETS\mirror\MirrorReflection.cs:86)
  
 (Filename: D:/Unity/GAME/Assets/Standard Assets/Effects/ImageEffects/Scripts/EdgeDetection.cs Line: 79)

Any ideas how to fix it, and why it works in editor but not in build? Thanks in advance!