Xamarin.Forms Exception:Didn't find class "com.symbol.emdk.EMDKManager"

Hello!

I'm using Xamarin.Forms .Net Standard to develop a scanner app.

I use below code in MainActivity.cs to init EMDKManager

     var emdk = Java.Lang.Class.ForName("com.symbol.emdk.EMDKManager");

But when i want to get it in DepencySerivces, system throw a Exception:Didn't find class "com.symbol.emdk.EMDKManager"

     EMDKManager.GetEMDKManager(Android.App.Application.Context, this)

Who can help to solve it??  Thanks!!

PS: AndroidManifest.xml has add users-library

<uses-permission android:name="com.symbol.emdk.permission.EMDK" />

<application android:label="Zebra Forms">

<uses-library android:name="com.symbol.emdk" android:required="false" />

</application>