It has to look like you~!
Casting Directors expect the person in that headshot to walk in the door. Because your headshot had a particular look that fit the need and you walk in with an entirely different look. You may have cut your hair, changed your hair color or just look younger in person and they wanted older.
In the eyes of the Casting Director you just pulled “The Bait and Switch” not on purpose or with ill intent but this is how they feel.
It has to represent you.
This one is different in nature than it has to look like you. This is your VIBE, your FEEL of your character. Your headshot has an edgy bad to the bone feel but you come into the room with out an edgy bone in your body, very timid in nature. The vibe you came into the room just does not match the vibe of your headshot.
It has to STAND OUT from the crowd in a positive way.
Standing out – breaking the noise is difficult but it is a prerequisite. If your headshot does not stand out it will not be seen let alone picked.
A great photographer that specializes in headshots for the market you want to work in is a good starting point. Great lighting, contrast, composition and a photographer that knows how to capture your “Sprit” your “Vibe” in a photograph are a must