alpha value not effective

drawing a cube with one face with alpha = 0.4
and rotating it, i am unable to see through this face.

i drew the cube using 6 glBegin(QUADS); segments. one of which has glColor4f(1,0,0,.4);

I also did glEnable(GL_ALPHA_TEST) ; any ideas why it might not be working ?

You should enable blending and define the glBlendFunc. Check out NeHe’s tutorials for simple examples.