Add screen of my app
I am creating an expense tracker app. There is a black button that should show snackbar. It shows but it does not show on The add Screen but on my screen as shown in the picture Home screen of my app. How should I fix this.

The function _saveExpense is pased from addScreen to Keyboard.dart in the widgets folder
this is the link to my github repo (https://github.com/mujtabafrhn2580/expense-tracker-app)

I tried to use Materialbanner istead but it also didn’t work