I know this question has been asked before, but the answers I've read don't seem to be working for me. I have a MS 90D refresh, which is about 3 weeks old. My California FastPass transponder is mounted in the car, but with no success. I've tried it in at least 5 different locations of the front windshield, with no luck (upper left, lower left, upper right, lower right, adjacent to the camera housing where there is no tint). I know it doesn't work because the transponder doesn't beep when I go through a toll and then a day later I check my account and it says I had a violation, then they auto debit my account, because it does a license plate match. I've had my plates for about 10 days, so I've verified it many times already. Prior to having plates, I must've just gotten lucky because they couldn't do a plate lookup, oh well Any advice on where I can place the transponder? I am at a loss. I've read that some folks have mounted it on the rear windshield, but that won't work for me - I want to be able to change the setting on the transponder to the number of occupants in the car, easily, without having to open the trunk before we start our drive.