Is one of your sims at the station working their shift? Can you post a screen shot?
Try restarting your device and/or restarting the fame app. Walk your sims around and see if anyone shows up. You could also try having another of your sims do the job at the same time. I had two sims working at the same time.
Here is a link to a blog that explains this occupation
https://thegirlwhogames.wordpress.com/2016/06/14/the-sims-freeplay-police-update/
try just walking your sim around the station to see if that gets it going. If that doesn't work and you've tried rebooting your device and/restarting the game app then you will need to contact support. You can do this using the 'question mark' in the game menu.
