Game works in unity editor but doesn't work correctly after building it.

Hey, so ... I'm having this issue. Was working on my game, testing everything in the unity editor and now I decided to build it. So, I do so and install the app on my phone (it is an android game) and the only thing I get when I open it is the "Made with Unity" starting logo and after that, it is just a blackscreen. The thing I added after last successful build is saving data using BinaryFormatter. Anyone who could help me? Really dunno what to do here!
Thanks in advance