Event tracker flutter still not saved on own database

I’ve tried to follow sample code to implement event tracker on my own flutter code from snowplow flutter documentation and sample code snowplow-flutter-tracker, but the result is still not saved the data into table event on my own database use cloud sql postgre and the server use snowplow community edition installed on gcloud. I put the snippet code disparate on analytics helper then I call those function on each screen in the app, can anyone give me insight or advice to fix this?
hopefully I can solve those issue under this forum, thanks a lot everyone.