Why my sora 2 showing 12 seconds video making and result only 4 seconds video generate why many time I try for 12 seconds video but it make only 4 seconds video

Sora 2 i not generating ai video longer than 4 seconds
I am generating ai video on sora 2 for 12 seconds. I am only getting 4 second videos and being charged for 12. 

Sora generated films are 4 seconds long instead 12 second, what is the reason? I choose 12 sek and describe it in prompt
Ive tried to ganerate 12 seconds film in sora 2 but it cuts after 4 seconds , what is the reason I think its some technical error.

Prompt

[A 12-second black-and-white cinematic film in classic documentary style, high-contrast, subtle film grain, shot on 35mm. 

Start with the exact provided photograph as the opening frame. Slowly transform it into a poetic visualization of string theory – the deepest truth we know about reality: everything in the universe is made of tiny, vibrating one-dimensional strings, not points. 

Camera work must be dynamic and varied:
- 0-3s: slow, majestic dolly zoom from wide cosmic shot into microscopic scale
- 3-6s: extreme close-up on a single vibrating string twisting and oscillating in 10-dimensional space
- 6-9s: smooth tracking shot following different vibration patterns turning into quarks, electrons, photons and gravitons – showing how one string creates all forces and particles
- 9-12s: elegant crane shot pulling back through curled-up extra dimensions, revealing glowing branes and hints of parallel universes

Elegant, mysterious, almost hypnotic atmosphere. Pure monochrome, no color, no text, no logos. Cinematic lighting, perfect composition, fluid motion, masterpiece quality.]