Angular 2 ‘component’ is not a known element

I’m trying to use a component I created inside the AppModule in other modules. I get the following error though:

“Uncaught (in promise): Error: Template parse errors:

‘contacts-box’ is not a known element:

1. If ‘contacts-box’ is an Angular component, then verify that it is part of this module.
2. If ‘contacts-box’ is a Web Component then add ‘CUSTOM_ELEMENTS_SCHEMA’ to the ‘@NgModule.schemas’ of this component to suppress this message.

My project structure is quite simple:

I keep my pages in pages directory, where each page is kept in different module (e.g. customers-module) and each module has multiple components (like customers-list-component, customers-add-component and so on). I want to use my ContactBoxComponent inside those components (so inside customers-add-component for example).

As you can see I created the contacts-box component inside the widgets directory so it’s basically inside the AppModule. I added the ContactBoxComponent import to app.module.ts and put it in declarations list of AppModule. It didin’t work so I googled my problem and added ContactBoxComponent to export list as well. Didn’t help. I also tried putting ContactBoxComponent in CustomersAddComponent and then in another one (from different module) but I got an error saying there are multiple declarations.

What am I missing?