Custon shaders on Flash

Hello.

I'm having some weird issues on a Flash build. Everything works fine in the editor, but once I build, things either don't work at all or look very different from how they looked in the editor. Here's the shader code for a mirror reflection shader:

 Shader "FX/Mirror Reflection" { 
 Properties {
     _MainTex ("Base (RGB)", 2D) = "white" {}
     _LightMapTex("LightMap (RGB)", 2D) = "white" {}
     _ReflectionControl ("Reflection Control", Color) = (0.7,0.7,0.7,0.9)
     _ReflectionTex ("Reflection", 2D) = "black" { TexGen ObjectLinear }
 }
 
 // two texture cards: full thing
 Subshader { 
     Lighting On
     Pass {
         SetTexture[_ReflectionTex]
         {
             matrix [_ProjMatrix]
             constantcolor [_ReflectionControl]
             combine constant lerp (constant) texture
         }
 
         SetTexture[_MainTex] { combine previous +- texture }
         SetTexture[_LightMapTex] {combine texture +- previous }
 
     }
 }
 
 // fallback: just main texture
 Subshader {
     Pass {
         SetTexture [_MainTex] { combine texture }
         SetTexture[_LightMapTex] {combine texture lerp (texture) previous }
     }
 }
 
 }

There's also code that sets up another camera that writes into the render texture.

This is how it looks in the editor:

And this is how it looks in the build:

In other words, all it draws is the lightmap...