Issues of setting a custom seekbar on xamarin android?

<SeekBar
android:progressDrawable="@drawable/seekbar"
...

In drawable/seekbar.xml

<layer-list  
  xmlns:android="http://schemas.android.com/apk/res/android">  
    <item android:id="@android:id/background" android:drawable="@drawable/seekbg" />  
    <item android:id="@android:id/secondaryProgress">  
        <clip>  
            <shape>  
               <corners android:radius="2.0dip" />  
               <gradient android:startColor="#80ffd300" android:endColor="#a0ffcb00" android:angle="270.0" android:centerY="0.75" android:centerColor="#80ffb600" />  
            </shape>  
        </clip>  
    </item>  
   <item android:id="@android:id/progress">  
       <clip android:drawable="@drawable/seek" />  
   </item>  
</layer-list>  

No resource found that matches the given name (at 'progressDrawable' with value '@drawable/seekbar').

How to solve it. Thanks