Angular2 build under angular-cli with directive and ng build --prod

I have an angular-cli app, when I add to package.json this

"angular2-auto-scroll": "1.0.12"

and in app.module.ts import it

import { Angular2AutoScroll } from "angular2-auto-scroll/lib/angular2-auto-scroll.directive";

and add it to declarations section ng build --prod fails with this error

ERROR in Unexpected value 'Angular2AutoScroll in C:/coding/workspace/myapp/myapp-web/node_modules/angular2-auto-scroll/lib/angular2-auto-scroll.directive.d.ts' declared by the module 'AppModule in C:/coding/workspace/myapp/myapp-web/app_code/app/app.module.ts'
ERROR in ./app_code/main.ts Module not found: Error: Can't resolve './$$_gendir/app/app.module.ngfactory' in 'C:\coding\workspace\myapp\myapp-web\app_code'
 @ ./app_code/main.ts 6:0-74
 @ multi ./app_code/main.ts

however when I build with just ng build without --prod then all build fine. Does anyone know what could be the reason? Or any other way I can import this npm package so it does not fail PROD build?

via Lucas