The com.google.android cannot be resolved

Hi everyone,

Sorry for my bad English, I'll try to write correctly.

I made an app with processing for android and I published it on play store as an alpha test. Now I want to put ads on the app but I have many troubles. First of all, processing cannot resolve the import of com.google.android. I added the line "compile 'com.google.android.gms:play-services-ads:11.8.0'" in the build.gradle in the "app" folder, as told by the official guide, but nothing changed.

has the problem already been solved? How can I solve it?

Thanks you all