Cannot get realtime data from FireBase database

Hi...I've been developing my apps for a while using firebase. My coding work on the screen I'm working on. So, I move on to next screen but when I come back to the previous one it doesn't work anymore. I'm pretty sure no change was made. Does anyone else have this problem. How to fix this. I don't want to re-do everything.

Use the last aia of your Project that you saved and reload the Project rather than redoing?