Build Error NGC

Hey there! I have an error when i build an android app.

[15:35:49]  ngc error: Error: Error at c:/myproject/ion2/.tmp/providers/film-service.ts:20:3: Return type of public method from exported class has or is using name 'Observable' from external module "c:/myproject/ion2/node_modules/rxjs/Observable" but cannot be named.
at check (c:\myproject\ion2\node_modules\@angular\tsc-wrapped\src\tsc.js:31:15)
at Tsc.typeCheck (c:\myproject\ion2\node_modules\@angular\tsc-wrapped\src\tsc.js:86:9)
at c:\myproject\ion2\node_modules\@angular\tsc-wrapped\src\main.js:33:23
at process._tickCallback (internal/process/next_tick.js:103:7)
at Module.runMain (module.js:592:11)
at run (bootstrap_node.js:394:7)
at startup (bootstrap_node.js:149:9)
at bootstrap_node.js:509:3

[15:35:49]  ngc error: Compilation failed


[15:35:49]  Error: Could not resolve entry (.tmp/app/
at c:\myproject\ion2\node_modules\rollup\dist\rollup.js:8602:28
at process._tickCallback (internal/process/next_tick.js:103:7)

Are you importing rxjs and Observable?

import ‘rxjs/Rx’;
import { Observable } from ‘rxjs/Observable’;

Thank you! Now all working!