title: missing ActionBar in material design
body: <p>I want to develop an Android app with AndroidStudio and the new material design and it looks great on Android 5.0 but when I test the app on my 4.4.2 phone, the ActionBar of the app is missing.</p>
  
  <p>Here is my Manifest:</p>
  
  <pre><code>&lt;application
      android:allowBackup="true"
      android:icon="@drawable/ic_launcher"
      android:label="@string/app_name"
      android:theme="@style/MyTheme" &gt;
      &lt;activity
          android:name=".MainActivity"
          android:label="@string/app_name" &gt;
          &lt;intent-filter&gt;
              &lt;action android:name="android.intent.action.MAIN" /&gt;
  
              &lt;category android:name="android.intent.category.LAUNCHER" /&gt;
          &lt;/intent-filter&gt;
      &lt;/activity&gt;
  &lt;/application&gt;
  </code></pre>
  
  <p>the styles.xml</p>
  
  <pre><code>&lt;resources&gt;
  
  &lt;!-- Base application theme. --&gt;
  &lt;style name="MyTheme" parent="Theme.AppCompat.Light"&gt;
  &lt;/style&gt;
  </code></pre>
  
  <p></p>
  
  <p>and the build.gradle</p>
  
  <pre><code>apply plugin: 'com.android.application'
  
  android {
      compileSdkVersion 21
      buildToolsVersion "21.0.0"
  
      defaultConfig {
          applicationId "com.example.app"
          minSdkVersion 14
          targetSdkVersion 21
          versionCode 1
          versionName "1.0"
      }
      buildTypes {
          release {
              runProguard false
              proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
          }
      }
  }
  
  dependencies {
      compile fileTree(dir: 'libs', include: ['*.jar'])
      compile 'com.android.support:appcompat-v7:+'
  }
  </code></pre>
  
  <p>Do you know where the error is?</p>
  
  <p>Thank you!
  Simon</p>