title: Android XML: RuntimeException: Failed to resolve attribute at index 6
body: <p>Hello dear stackoverflower,</p>
  
  <p>In my project, i am using the new "android design library".
  The problem is, that there is a runtime exception which says(Im trying to create a FloatingButton):</p>
  
  <pre><code> java.lang.RuntimeException: Failed to resolve attribute at index 6
          at android.content.res.TypedArray.getColorStateList(TypedArray.java:426)
          at android.support.design.widget.FloatingActionButton.&lt;init&gt;(FloatingActionButton.java:91)
          at android.support.design.widget.FloatingActionButton.&lt;init&gt;(FloatingActionButton.java:79)
          at android.support.design.widget.FloatingActionButton.&lt;init&gt;(FloatingActionButton.java:75)
  </code></pre>
  
  <p>I was able to figure out, which the attribute cannot be resolved :</p>
  
  <pre><code>&lt;style name="Widget.Design.FloatingActionButton" parent="android:Widget"&gt;
      &lt;item name="android:background"&gt;@drawable/fab_background&lt;/item&gt;
      &lt;item name="backgroundTint"&gt;?attr/colorAccent&lt;/item&gt;  **!! this one is missing !!**
      &lt;item name="fabSize"&gt;normal&lt;/item&gt;
      &lt;item name="elevation"&gt;@dimen/fab_elevation&lt;/item&gt;
      &lt;item name="pressedTranslationZ"&gt;@dimen/fab_translation_z_pressed&lt;/item&gt;
      &lt;item name="rippleColor"&gt;?attr/colorControlHighlight&lt;/item&gt;
      &lt;item name="borderWidth"&gt;@dimen/fab_border_width&lt;/item&gt;
  &lt;/style&gt;
  </code></pre>
  
  <p>This is located in res/values/styles/styles.xml in the android-design-library</p>
  
  <p>i have read in <a href="https://stackoverflow.com/questions/27791290/no-resource-identifier-found-for-attribute-backgroundtint-in-package-android">this</a> post that the API lvl should bis 21+. But as the design library supports API 7+, this should not be a problem actually.</p>
  
  <p>It is also worth to mention that i have not included the design library as a gradle-dependency like this:</p>
  
  <pre><code> compile 'com.android.support:design:22.2.0'
  </code></pre>
  
  <p>I am adding the library manually to the project because the Jenkins server has no Internet access.
  I have updated the support-v4 library to 21.2.0
  also the appcompat support-v7 is included and updated.</p>
  
  <p>Here is the android-design-library gradle file:</p>
  
  <pre><code>android {
  compileSdkVersion 21
  buildToolsVersion "21.1.2"
  
  defaultConfig {
      minSdkVersion 17
      targetSdkVersion 21
  }
  
  buildTypes {
      release {
          minifyEnabled false
          proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.txt'
      }
  }
  </code></pre>
  
  <p>It would be great if someone can help me.</p>