u/Infamous-Pay4297

I tried to put on a tetherspout but it doesn't work. I've tried it several times but i can't fix it the way i want. I used a 10 mm ring with on a 8 mm shaft of the tetherspout. Maybe I pushed it not deep enough to get it fixed. How deep should the ring be from top? Or is 10 mm to small? Can someone help me?