XML : emojicon is not bound

I am implementing the emojicon library in my android project, but when I try to this error comes out:

Namespace emojicon is not bound

Here's the xml I am using:

      <com.rockerhieu.emojicon.EmojiconTextView      android:id="@+id/txtEmojicon"      android:text="I \ue32d emojicon"      android:layout_width="match_parent"      android:layout_height="wrap_content"/>    <com.rockerhieu.emojicon.EmojiconEditText      android:id="@+id/editEmojicon"      android:text="I \ue32d emojicon"      emojicon:emojiconSize="28sp"      android:layout_width="match_parent"      android:layout_height="wrap_content"/>  <fragment      android:id="@+id/emojicons"      android:layout_width="match_parent"      android:layout_height="220dp"      class="com.rockerhieu.emojicon.EmojiconsFragment"/>    

Please help.