First dash app / deployment issue

I followed the instructions here exactly and got no error messages. However, when i deploy (on heroku or locally), there’s dropdown box but nothing much else. Is that all that’s meant to be there (I was expecting a plot as well)

EDIT: I replaced the code in with the code provided here (a different, but also very simple, app), and it seems to work just fine - I now see a chart on the screen

FURTHER EDIT: The replacement chart works on immediately, but when deploying to heroku, change

app = dash.Dash()


app = dash.Dash()
server = app.server

That’s it - it will now work on heroku!