Sharp edge crease, Blackline

Hello Blenders,
I’m working on a watch and,
I have a problem with (sharp edge) crease. In the pict you see a blackline. Even when i’m putting a white screen in the background , the black line is still visible. On every camera angel I see this. sometime more /less. When I disable the crease and put support edge line its gone.

What is the problem??:open_mouth::open_mouth:

And it is no reflextion

check double verts or faces and normals

and show nodes set up

which renderer is it ?

try to put that part somewhere else and see if black line is still there

happy cl