If you're sure they are inside the camera's view, it's probably because of the winding.
glDisable(GL_CULL_FACE);
glLightModeli(GL_LIGHT_MODEL_TWO_SIDE, 1);
will enable two sided rendering for all polly's
glDisable(GL_CULL_FACE);
glLightModeli(GL_LIGHT_MODEL_TWO_SIDE, 1);
will enable two sided rendering for all polly's