After change navigation drawer item's icon, app is dead
<p>I downloaded icons for navigation drawer items at <a href="http://google.github.io/material-design-icons/" rel="nofollow">here</a> <br>
And I changed my drawer item icons. And then, I tried to run my app. <br>
But, my app is not working. It was fine before change icons.</p>

<p>I just moved <code>xml</code> files of icons to <code>drawable-v21</code> folder. </p>

<blockquote>
  <p>Here is the message.</p>
</blockquote>

<pre><code>E/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.hsk.hallymexam, PID: 11979
    java.lang.RuntimeException: Unable to start activity ComponentInfo

    {com.hsk.hallymexam/com.hsk.hallymexam.MainActivity}: android.view.InflateException: Binary XML file line #22: Error inflating class android.support.design.widget.NavigationView
    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2436)
    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2495)
    at android.app.ActivityThread.access$900(ActivityThread.java:170)
    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1304)
    at android.os.Handler.dispatchMessage(Handler.java:102)
    at android.os.Looper.loop(Looper.java:146)
    at android.app.ActivityThread.main(ActivityThread.java:5635)
    at java.lang.reflect.Method.invokeNative(Native Method)
    at java.lang.reflect.Method.invoke(Method.java:515)
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1291)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1107)
    at dalvik.system.NativeStart.main(Native Method)
    Caused by: android.view.InflateException: Binary XML file line #22: Error inflating class android.support.design.widget.NavigationView
    at android.view.LayoutInflater.createView(LayoutInflater.java:626)
    at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:702)
    at android.view.LayoutInflater.rInflate(LayoutInflater.java:761)
    at android.view.LayoutInflater.inflate(LayoutInflater.java:498)
    at android.view.LayoutInflater.inflate(LayoutInflater.java:398)
    at android.view.LayoutInflater.inflate(LayoutInflater.java:354)
    at android.support.v7.app.AppCompatDelegateImplV7.setContentView(AppCompatDelegateImplV7.java:280)
    at android.support.v7.app.AppCompatActivity.setContentView(AppCompatActivity.java:140)
    at com.hsk.hallymexam.MainActivity.onCreate(MainActivity.java:42)
    at android.app.Activity.performCreate(Activity.java:5580)
    at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1093)
    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2400)
    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2495) 
    at android.app.ActivityThread.access$900(ActivityThread.java:170) 
    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1304) 
    at android.os.Handler.dispatchMessage(Handler.java:102) 
    at android.os.Looper.loop(Looper.java:146) 
    at android.app.ActivityThread.main(ActivityThread.java:5635) 
    at java.lang.reflect.Method.invokeNative(Native Method) 
    at java.lang.reflect.Method.invoke(Method.java:515) 
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1291) 
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1107) 
    at dalvik.system.NativeStart.main(Native Method) 
    Caused by: java.lang.reflect.InvocationTargetException
    at java.lang.reflect.Constructor.constructNative(Native Method)
    at java.lang.reflect.Constructor.newInstance(Constructor.java:423)
    at android.view.LayoutInflater.createView(LayoutInflater.java:600)
    at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:702) 
    at android.view.LayoutInflater.rInflate(LayoutInflater.java:761) 
    at android.view.LayoutInflater.inflate(LayoutInflater.java:498) 
    at android.view.LayoutInflater.inflate(LayoutInflater.java:398) 
    at android.view.LayoutInflater.inflate(LayoutInflater.java:354) 
    at android.support.v7.app.AppCompatDelegateImplV7.setContentView(AppCompatDelegateImplV7.java:280) 
    at android.support.v7.app.AppCompatActivity.setContentView(AppCompatActivity.java:140) 
    at com.hsk.hallymexam.MainActivity.onCreate(MainActivity.java:42) 
    at android.app.Activity.performCreate(Activity.java:5580) 
    at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1093) 
    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2400) 
    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2495) 
    at android.app.ActivityThread.access$900(ActivityThread.java:170) 
    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1304) 
    at android.os.Handler.dispatchMessage(Handler.java:102) 
    at android.os.Looper.loop(Looper.java:146) 
    at android.app.ActivityThread.main(ActivityThread.java:5635) 
    at java.lang.reflect.Method.invokeNative(Native Method) 
    at java.lang.reflect.Method.invoke(Method.java:515) 
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1291) 
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1107) 
    at dalvik.system.NativeStart.main(Native Method) 
    Caused by: android.content.res.Resources$NotFoundException: Resource ID #0x7f020050
    at android.content.res.Resources.getValue(Resources.java:2326)
    at android.support.v7.widget.AppCompatDrawableManager.loadDrawableFromDelegates(AppCompatDrawableManager.java:321)
    at android.support.v7.widget.AppCompatDrawableManager.getDrawable(AppCompatDrawableManager.java:197)
    at android.support.v7.widget.AppCompatDrawableManager.getDrawable(AppCompatDrawableManager.java:192)
    at android.support.v7.view.menu.MenuItemImpl.getIcon(MenuItemImpl.java:421)
    at android.support.design.internal.NavigationMenuPresenter$NavigationMenuAdapter.prepareMenuItems(NavigationMenuPresenter.java:495)
    at android.support.design.internal.NavigationMenuPresenter$NavigationMenuAdapter.update(NavigationMenuPresenter.java:436)
    at android.support.design.internal.NavigationMenuPresenter.updateMenuView(NavigationMenuPresenter.java:112)
    at android.support.design.widget.NavigationView.inflateMenu(NavigationView.java:245)
    at android.support.design.widget.NavigationView.&lt;init&gt;(NavigationView.java:169)
    at android.support.design.widget.NavigationView.&lt;init&gt;(NavigationView.java:95)
    at java.lang.reflect.Constructor.constructNative(Native Method) 
    at java.lang.reflect.Constructor.newInstance(Constructor.java:423) 
    at android.view.LayoutInflater.createView(LayoutInflater.java:600) 
    at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:702) 
    at android.view.LayoutInflater.rInflate(LayoutInflater.java:761) 
    at android.view.LayoutInflater.inflate(LayoutInflater.java:498) 
    at android.view.LayoutInflater.inflate(LayoutInflater.java:398) 
    at android.view.LayoutInflater.inflate(LayoutInflater.java:354) 
    at android.support.v7.app.AppCompatDelegateImplV7.setContentView(AppCompatDelegateImplV7.java:280) 
    at android.support.v7.app.AppCompatActivity.setContentView(AppCompatActivity.java:140) 
    at com.hsk.hallymexam.MainActivity.onCreate(MainActivity.java:42) 
    at android.app.Activity.performCreate(Activity.java:5580) 
    at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1093) 
    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2400) 
    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2495) 
    at android.app.ActivityThread.access$900(ActivityThread.java:170) 
    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1304) 
    at android.os.Handler.dispatchMessage(Handler.java:102) 
    at android.os.Looper.loop(Looper.java:146) 
    at android.app.ActivityThread.main(ActivityThread.java:5635) 
    at java.lang.reflect.Method.invokeNative(Native Method) 
    at java.lang.reflect.Method.invoke(Method.java:515) 
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1291) 
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1107) 
    at dalvik.system.NativeStart.main(Native Method)
</code></pre>

<p>Did I do something wrong?</p>