No shadow gradient - Urgent

Hi,
I have a scene where I want some gradient starting from the window border. But I tried everything I could and I’m stuck some a general ambient without any trace of gradient.
I have a stationary sunlight, a movable skylight and some spotlights.
AO is on.
I’ve been stuck for 2 days, it’s urgent that I finish my scene soon. Thank you very much for your time.