title: databinding does not exist: How to solve it?
body: <p>I'm working on an Android application with databinding but I've always next error:</p>
  
  <blockquote>
    <p><strong>Error:</strong> Package <code>my.package.databinding</code> does not exist.</p>
  </blockquote>
  
  <p>Here is my <code>build.gradle</code> on project level:</p>
  
  <pre><code>buildscript {
      repositories {
          jcenter()
      }
      dependencies {
          classpath 'com.android.tools.build:gradle:2.2.2'
      }
  }
  allprojects {
      repositories {
          jcenter()
      }
  }
  task clean(type: Delete) {
      delete rootProject.buildDir
  }
  </code></pre>
  
  <p>I've also enabled binding in the <code>build.gradle</code> file on module level.</p>
  
  <p>Now my question is, why occurs this error and how could I solve it?</p>