I have a customer module with customer-routing module:
const routes: Routes = [
  {
    path: '', component: CustomerComponent,
    children: [
      { path: 'edit', component: EditCustomerComponent }
    ]
  }
];
And this is my app-routing module: 
const routes: Routes = [
  { path: 'customers/:id', loadChildren: './customer/customer.module#CustomerModule' },
  { path: 'login', component: LoginComponent}
];
But when I follow such path customers/3/edit it shows me always CustomerComponent not EditCustomerComponent.
Maybe lazy loading doesn't work?
PS: I am using angular 6.1.0
Update: My customer module
import {ReactiveFormsModule} from '@angular/forms';
import {CustomerComponent} from './customer.component';
import {EditCustomerComponent} from './edit-customer.component';
@NgModule({
  imports: [
    CommonModule,
    CustomerRoutingModule,
    ReactiveFormsModule
  ],
  declarations: [CustomerComponent, EditCustomerComponent]
})
export class CustomerModule { }
 
    