ViewModelProviders is not working inside my Fragment

Fragments offer a helper method for retrieving a non-null Activity - requireActivity(). Use that instead of activity:

viewModel = ViewModelProviders.of(requireActivity()).get(SharedViewModel::class.java)

As an alternative, you can include the fragment-ktx dependency in your app and use the by activityViewModels() Kotlin property extension instead of using ViewModelProviders.of() at all:

val viewModel: SharedViewModel by activityViewModels()