android - Navigation View selecting multiple items -

i implemented navigation view (support library 24.0.0):

but strange behavior occurred in have been trying control since.

here drawer.xml

<?xml version="1.0" encoding="utf-8"?> <menu xmlns:android="http://schemas.android.com/apk/res/android">     <item android:title="categories">         <menu>             <group android:checkablebehavior="single">                 <item                     android:id="@+id/navigation_item_1"                     android:icon="@drawable/ic_news"                     android:title="top stories" />                 <item                     android:id="@+id/navigation_item_2"                     android:icon="@drawable/ic_music"                     android:title="entertainment" />                 <item                     android:id="@+id/navigation_item_3"                     android:icon="@drawable/ic_sport"                     android:title="sport" />                 <item                     android:id="@+id/navigation_item_4"                     android:icon="@drawable/ic_lifestyle"                     android:title="lifestyle" />                 <item                     android:id="@+id/navigation_item_5"                     android:icon="@drawable/ic_tech"                     android:title="technology" />                 <item                     android:id="@+id/navigation_item_6"                     android:icon="@drawable/ic_world"                     android:title="international" />              </group>         </menu>     </item>  </menu> 

but result :

in 1 should selected.

show code of navigation drawer.there no problem in above layout