light GL_SPECULAR doesn't work ?

I have code:

GLfloat Light[] = {1.0f, 1.0f, 0.0f, 1.0f}; 
GLfloat LightPosition[] = {0.0f, 0.0f, 3.0f, 1.0f};

glLightfv(GL_LIGHT0, GL_AMBIENT, Light); 
glLightfv(GL_LIGHT0, GL_DIFFUSE, Light); 
glLightfv(GL_LIGHT0, GL_SPECULAR, Light); //I can delete it
glLightfv(GL_LIGHT0, GL_POSITION, LightPosition);

I can delete glLightfv(GL_LIGHT0, GL_SPECULAR, Light); and I see no difference - why ?

Specular highlights can only be seen at some angles, when light bounce on mirror-like surface towards the camera.
Try to choose a better angle.

And to make the specular stand out, give it a different color like white color

GLfloat white[4]={1.0f,1.0f,1.0f,1.0f};
glLightfv(GL_LIGHT0, GL_SPECULAR, white);

thx people