The police station has certain things that must be there in order to work correctly. (same with hospital and science lab) If you edit or replace a "hidden lot" there is a potential of causing problems with career advancement. Even if you replaced it in a different save, the other replacement may have worked and this one doesn't.
If you saved the original police station, you can test this. Open the original police station in build mode, save the cell (where all criminals are usually locked) as a room to your gallery and then place it in your custom police station. This would replace the cells with the one that has all the required components.
Remember, it isn't guaranteed that another problem might come up if you don't have the other required items in place. Of course, you could just replace the police station with the original one and go from there.
Let us know if this helps. Happy Simming!