blind spot camera tap into mirror signal

[bumpersignal]

I bought a weivision 360 bird's eye view system. I've got it all working excep that the side cameras do not sense blinkers. Each camera has a positive lead that should be tapped into blinker light, which I believe is the brown wire in each of the side mirrors. I tested with a 12v circuit light tester that it sees the blinker as expected, yet the weivision still doesn't detect blinker activity. I tested if the weivision works by connecting a constant 12v to the camera lead and that appears to work. Any suggestions?

[mkguitar]

I might guess that a "flashing" power source isn't giving the camera power long enough to boot up.