title: Failed to set up SDK: Error:Module 'app': platform 'Google Inc.:Google APIs:21' not found
body: <pre><code>Failed to set up SDK: Error:Module 'app': platform 'Google Inc.:Google APIs:21' not found.
  </code></pre>
  
  <p>At a complete loss as to why this isn't working. Attempted to update my SDK to 23 but realized I wasn't prepared to deal with all the new deprecations, etc., so I reverted to an older version on Mercurial. I've done literally nothing else, and the reversion should have solved everything. Unfortunately, I'm stuck unable to connect my app and build it. I've even reinstalled Android Studio from scratch, but I continue to receive the same warning and my app won't build at all. What could possibly be going wrong?</p>
  
  <p>Here is my build gradle:</p>
  
  <pre><code>apply plugin: 'com.android.application'
  
  android {
      compileSdkVersion 'Google Inc.:Google APIs:21'
      buildToolsVersion '21.1.2'
  
      defaultConfig {
          applicationId "com.elgami.customizer"
          minSdkVersion 14
          targetSdkVersion 21
      }
  
      buildTypes {
          release {
              minifyEnabled false
              //runProguard false
              //proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.txt'
          }
      }
  }
  
  repositories {
      mavenCentral()
      maven { url "https://jitpack.io" }
  }
  
  dependencies {
      compile 'com.ogaclejapan.smarttablayout:library:1.5.0@aar'
      compile 'com.github.antonyt:InfiniteViewPager:v1.0.0'
      compile 'com.android.support:appcompat-v7:22.2.0'
      // recyclerview
      compile 'com.android.support:recyclerview-v7:23.1.1'
      // google analytics
      compile 'com.google.android.gms:play-services-analytics:8.3.0'
      // pager sliding strip
      compile 'com.astuetz:pagerslidingtabstrip:1.0.1'
      // http library (for using beanstream REST)
      compile 'org.apache.httpcomponents:httpclient-android:4.3.5.1'
      // amaazon S3 uploads
      compile 'com.amazonaws:aws-android-sdk-s3:2.1.+'
      // paypal purchasing
      compile files('libs/PayPalAndroidSDK-2.7.1.jar')
      // Module dependency on ParseLoginUI library sources
      compile project(':ParseLoginUI')
      // Parse libs
      compile files('libs/ParseCrashReporting-1.9.2.jar')
      compile files('libs/Parse-1.9.1.jar')
      compile files('libs/ParseFacebookUtilsV4-1.9.1.jar')
      // android support v4
      compile files('libs/android-support-v4.jar')
      // facebook SDK
      compile 'com.facebook.android:facebook-android-sdk:4.1.0'
      //butterknife
      compile 'com.jakewharton:butterknife:6.1.0'
      // Subsampling-scale-image-view (for templating)
      //compile 'com.davemorrissey.labs:subsampling-scale-image-view:3.1.4'
      compile files('libs/AppRater.jar')
  }
  </code></pre>