Smart lighting motion sensor range problem

I have set, in the app, the sensitivity for my motion sensor to high. I turned the light sensor threshold to 10. I waited until 9pm at night. My sensor is mounted to my lamppost which is about 15 feet from the bridge. It is mounted at a height of about 5 feet. Batteries are all new and register 100% in the app. And yet, I can walk straight up the motion sensor and it won't register motion until I'm 5-6 feet away from it. What am I doing wrong? So frustrated. Any suggestions would be greatly appreciated.