Fitbit flex bra clip

Hi guys.- I walk stroller most of the time and My Fitbit Flex won't work on the wrist when you touch stroller so I read some forums and many people clips on bra and it works fine. So I ordered this magnet clip that I can use Fitbit flex on my bra. However I tried it on and it didn't count step?!? Does anyone know how to wear it on properly? Face down face up or which part of bra to wear please?