You can verify this for yourself. When it's dark out, shine a light at your wheel reflector. You will see that it sort of shines back at you. This is "reflection." Next look at your reflector in daylight. Even if you point a light at it you will see very little reflection, it is lost amid the ambient daylight. This is normal and nothing to be concerned about. If you are worried about being seen in daylight, the bike shop can sell you a bright flag on a pole.
