No provider for service - when importing an external module

I built an Angular Module that imports IonicModule and has it’s own service and components:

  declarations: [ FileUploader],
  exports: [ FileUploader ],
  imports: [ 
  providers: [ FileService ],
export class FilesModule { }

then I import it to my AppModule (root):

  declarations: [ AppComponent ],
  entryComponents: [ AppComponent ],
  imports: [ 
export class AppModule { }

When I inject the FileService to the AppComponent I get an ERROR:

Error in AppComponent: No Provider for FileService

From Angular docs:

When we import a module, Angular adds the module’s service providers (the contents of its providers list) to the application root injector.

This makes the provider visible to every class in the application that knows the provider’s lookup token.

I believe that it has something to do with the way ionic starts the AppComponent
Because this simply works in a regular Angular app.
What am I missing to make this work?

I’m doing this same thing in ionic with no issues, seems strange. I have to believe something else is wrong.

I found it!
It was one of my pages that was still importing the old FileService from the AppModule level and not from the FilesModule level.
I wonder why I get Error in AppComponent and not in the page with the wrong import…