how to define the entry component in the child module ?

Question

I want to set the entry component in the user child module. It doesn't work. But, when i set it in the parent app module, it's work correctly. why ???

//User module
@NgModule({
imports: [],
exports: [UsersFormsComponent],
declarations: [UsersFormsComponent],
providers: [],
entryComponents : {
 UsersFormsComponent
}
})
export class UsersModule { }

// app module
@NgModule({
imports: [UsersModule],
exports: [],
declarations: [AppComponent],
providers: [],
})
export class AppModule { }