title: Android Studio 2.3.3: Failed to resolve: com.google.android.gms:play-services-ads:11.8.0 even with Maven
body: <p>I'm working on one of my first apps on Android Studio and want to add advertisements to it using Admob. In my gradle: project I have Maven:</p>
  
  <pre><code>buildscript {
  repositories {
      jcenter()
  }
  dependencies {
      classpath 'com.android.tools.build:gradle:2.2.3'
  
      // NOTE: Do not place your application dependencies here; they belong
      // in the individual module build.gradle files
  }
  }
  
  allprojects {
  repositories {
      jcenter()
  
      maven {
          url "https://maven.google.com"
      }
  }
  }
  
  task clean(type: Delete) {
  delete rootProject.buildDir
  }
  </code></pre>
  
  <p>Here is my app-level build.gradle dependencies as well</p>
  
  <pre><code>dependencies {
  compile fileTree(dir: 'libs', include: ['*.jar'])
  androidTestCompile('com.android.support.test.espresso:espresso-core:2.2.2', {
      exclude group: 'com.android.support', module: 'support-annotations'
  })
  
  compile 'com.android.support:appcompat-v7:23.4.0'
  compile 'com.google.android.gms:play-services-ads:11.8.0'
  compile 'com.android.support:design:23.4.0'
  testCompile 'junit:junit:4.12'
  
  }
  </code></pre>
  
  <p>Even though I have Maven in repositories I still get the error message: 
  Failed to resolve: com.google.android.gms:play-services-ads:11.8.0</p>
  
  <p>Shouldn't maven {url "<a href="https://maven.google.com" rel="nofollow noreferrer">https://maven.google.com</a>"} be enough to import the Mobile Ads sdk?</p>