My goal is to have a directional light source steming from the upper left corner of the screen regardless of the scene's transformations. I'm obviously missing something since the lighting is doesn't always seam to stem from the appropriate location when I rotate the scene.

// Application Side:
Code :
float light[4] = {-1.0, 1.0, -1.0, 0};
glLightfv(GL_LIGHT0, GL_POSITION, light);

// Vertex Shader
Code :
#version 120
varying vec2 multiTexCoord;
void main () {
  multiTexCoord = gl_MultiTexCoord0.xy;
  gl_Position = ftransform();
}

// Fragment Shader
Code :
#version 120
uniform sampler2D grndTexture;
uniform sampler2D normalTexture;
uniform sampler2D colorTexture;
varying vec2 multiTexCoord;
void main () {
  vec2 terCord = vec2 (multiTexCoord.x * 127.0 / 20.0, multiTexCoord.y * 127.0 / 20.0);
  vec3 n = normalize(texture2D(normalTexture, multiTexCoord).xyz);
  vec3 t = texture2D(grndTexture, terCord).xyz;
  vec3 l = normalize(gl_LightSource[0].position.xyz);
  vec3 c = texture2D(colorTexture, multiTexCoord).xyz;
  float diffuse = min(dot(n, l), 0.8);\n"
  vec3 final = c * t * diffuse;
  gl_FragColor = vec4 (final.r, final.g, final.b, 1.0);
}

Can anyone point out where my brain's malfunctioning here?