using shader question

I have a shader,it's role is change the color of picture,like follows:
<languageVersion : 1.0;>
kernel NewFilter
<   namespace : "Your Namespace";
    vendor : "Your Vendor";
    version : 1;
    description : "your description";
>
{
    input image4 src;
    output pixel4 dst;
    void
    evaluatePixel()
    {
        pixel4 px = sampleNearest(src,outCoord());
        px.rb=px.br;
        dst=px;
    }
}

Above code can run well under Pixel Bender,and can change the color of picture,then I export it as test.pbj.Then I call it under ActionScript3,the code is follows:
package{
import flash.display.Bitmap;
import flash.display.Shader;
import flash.display.Sprite;
import flash.filters.ShaderFilter;
import flash.utils.ByteArray;

[SWF(width=700,height=500,backgroundColor=0x000000)]

public class playTest extends Sprite{

[Embed(source='test.pbj',mimeType='application/octet-stream')]
private static const DesaturateKernel:Class;

[Embed(source='test.jpg')]
private static const BitmapClass:Class;

public function playTest(){
var bitmap:Bitmap=new BitmapClass() as Bitmap;
var byteArray:ByteArray=new DesaturateKernel() as ByteArray;
var shader:Shader=new Shader(byteArray);
var filter:ShaderFilter=new ShaderFilter(shader);
bitmap.filters=[filter];
addChild(bitmap);
}
}
}

When I run above code,I find the color of picture don't change! Why? Where is wrong?
Thanks