The Speedlite is not attached securely to the camera Attach the Speedlite's mounting foot securely to the camera The electrical contact of the Speedlite and the camera are dirty Clean the contact with a clean dry cloth If the Pilot light is red and is then pushed in and the Speedlite does not fire possibly The flash needs to be serviced
It enables you to see the shadow effect on the subject and the lighting balance. You can fire the modeling flash for wireless and normal flash shooting.