GLSL uniform not accessable

Hi, this code:
   glGetUniformLocationArb(shader_program, "red");
returns -1.

The "shader_program" is what I passed to glUseProgramObjectArb before.

I don't provide a vertex shader. My fragment shader code seems to be
loaded 
and working and is:

(BTW: I don't set the "image" in my main code anywhere, but I can access
the 
texture)

 # # #
uniform sampler2D image;
uniform float red, green, blue;

void main()
{
 vec4 texel = texture2D(image, gl_TexCoord[0].xy).rgba;

    if(texel.a > 0.001)
    {
      if(abs(texel.g - texel.r) < 0.0001) // black -> recolor
      {
        gl_FragColor = vec4(red, green, blue, texel.a);
      }
      else // blue eyes
      {
        gl_FragColor = texel;
      }
    }
    else // transparent
    {
      gl_FragColor = vec4(0,0,0.0, 0.0);
    }
}
 # # #



-- 
------------------------------------
Gernot Frisch
http://www.glbasic.com