Facebook Marketing API : Get results and cost per result of a Campaign

_x000D_ _x000D_ I'm creating an application (using Facebook Business Java SDK) that can get all infomation of campaigns own by an Ad Account. Almost of my campaigns have same objective is APP_INSTALLS. I want to know how many time my app was installed, so I tried to request infomation like "Results" column and "Cost per Result" column in Adsmanager board : Adsmanager colums But when I added "results" and "cost_per_result" to APIRequestGetInsights's request fields, I got a FailRequestException : "{"error":{"message":"(#100) results, cost_per_result are not valid for fields param. please check https://developers.facebook.com/docs/marketing-api/reference/ads-insights/ for all valid values","type":"OAuthException","code":100,"fbtrace_id":"DnPCKyIGIqs"}}" I used an user access token with permissions below : - read_insights - manage_pages - pages_show_list - publish_pages - ads_management - ads_read - business_management I searched on google many times but nothing is useful. So someone here please tell me how to get "Results" and "Cost per Result" info of a campaign by Facebook api?