title: "Material doesn't have a ... property" when using more than 3 2D Textures
body: <p>I wrote multiple <code>fixed function Shaders</code>. I noticed that as soon as the Shader contains more than 3 2D Textures, the Shader breaks and unity reporty the <code>Material doesn't have a ... property</code> for every property... the material has. For example:</p>
  
  <pre><code>Shader "Custom/JustAnotherShader" {
      Properties{
          _MainTex("Base (RGB)", 2D) = "white" { }
          _TexA("Another Texture", 2D) = "black" { }
          _TexB("Yet Another Texture", 2D) = "" { }
          _TexC("One More Another Texture", 2D) = "" { }
      }
  
      SubShader {
          Pass {
              SetTexture[_MainTex] { combine texture }
              SetTexture[_TexA] { combine texture * previous }
              SetTexture[_TexB] { combine texture + previous }
              SetTexture[_TexC] { combine texture - previous }
          }
      }
  
      Fallback Off
  }
  </code></pre>
  
  <p>This code would report this error for <code>_MainTex</code>, <code>_TexA</code>, <code>_TexB</code> and <code>_TexC</code>. This seems to be a bug. How to solve this problem?</p>