shader.setSample invalid uniform value I'm having troubles with my "clouds" texture while trying to sample it into my shader, the error is "invalid uniform value: clouds"

def main():
    import bge
    cont = bge.logic.getCurrentController()
    object = cont.owner

    for mesh in object.meshes:
        for material in mesh.materials:
            shader = material.getShader()
            if shader != None:
                shader.setSource(vertex_shader, fragment_shader, True)
                shader.setSampler("clouds", 0)

vertex_shader = """
uniform sampler2D clouds;
void main()
{ 
    gl_Position = ftransform();
}
"""

fragment_shader ="""

void main()
{
    vec4 color = vec4(1.0, 0.0, 0.0, 1.0);
    gl_FragColor = color;
}
"""
main()


I'd really appreciate some help here.
Check the Color Option under the Influence section of the Texture panel.