Pass the Context between classes inside Android plugin

Greetings.

Im kinda new with android plugins for unity and im trying to create an Alert Dialog after receibing a Broadcast but my application crashes right before that.

Here is my Manifest file

 <?xml version="1.0" encoding="utf-8"?>
 <manifest xmlns:android="http://schemas.android.com/apk/res/android"
     package="com.test.fenrir.broadcastunity"
     android:versionCode="1"
     android:versionName="1.0">
     <uses-sdk android:minSdkVersion="9" />
     <uses-permission android:name="android.permission.INTERNET"></uses-permission>
     <uses-permission android:name="android.permission.GET_ACCOUNTS" />
     <uses-permission android:name="com.google.android.c2dm.permission.RECEIVE" />
 
     <permission android:name="com.test.fenrir.broadcastunity.permission.C2D_MESSAGE"
         android:protectionLevel="signature" />
     <uses-permission android:name="com.test.fenrir.broadcastunity.permission.C2D_MESSAGE" />
     <application
         android:label="@string/app_name">
         <receiver android:name="MyReceiver" >
             <intent-filter>
                 <action android:name="com.test.fenrir.broadcastunity.Broadcast">
                 </action>
             </intent-filter>
         </receiver>
         <activity android:name="com.test.fenrir.broadcastunity.MainActivity" android:label="@string/app_name">
             <intent-filter>
                 <action android:name="android.intent.action.MAIN" />
                 <category android:name="android.intent.category.LAUNCHER" />
             </intent-filter>
         </activity>
     </application>
 </manifest>

My Sender Class

 public class MySender
 {
     private Context ctxt;
     private String _code;
     private static MySender instance;
     public int notificationIndex = 0;
 
     public MySender() {
         this.instance = this;
     }
 
     public static MySender instance() {
         if(instance == null) {
             instance = new MySender();
         }
         return instance;
     }
 
     public void setContext(Context context) {
         this.ctxt = context;
     }
 
     public void LaunchBroadcast()
     {
         Log.i("MySender2", "Trying to launch new broadcast2");
         Intent intent = new Intent();
         intent.addFlags(Intent.FLAG_INCLUDE_STOPPED_PACKAGES);
         intent.setAction("com.test.fenrir.broadcastunity.Broadcast");
         ctxt.sendBroadcast(intent);
     }
 }

My Receiver

 public class MyReceiver extends BroadcastReceiver {
 
     Context ctx;
     @Override
     public void onReceive(Context context, Intent intent) {
         this.ctx = context;
         Log.i("TestBroadcast", "Si estas leyendo esto, el broadcast funciona");
         CallAlert();
     }
 
     void CallAlert()
     {
         ProgressDialog progressDialog = new ProgressDialog(this.ctx);
         progressDialog.setProgressStyle(ProgressDialog.STYLE_SPINNER);
         progressDialog.setMessage("Intent Detected");
         progressDialog.setProgress(0);
         progressDialog.setMax(100);
         progressDialog.show();
     }
 }

And my C# script for unity

 using UnityEngine;
 using System.Collections;
 using UnityEngine.UI;
 
 public class Broadcast : MonoBehaviour {
     public Text _text;
     AndroidJavaObject instance = null;
     AndroidJavaObject activityInstance = null;
     AndroidJavaObject activityContext = null;
 
     public void CallBroadcast()
     {
         using(AndroidJavaClass activityClass = new AndroidJavaClass("com.unity3d.player.UnityPlayer"))
         {
             activityContext = activityClass.GetStatic<AndroidJavaObject>("currentActivity");
         }
         using(AndroidJavaClass pluginClass = new AndroidJavaClass("com.test.fenrir.broadcastunity.MySender")) {
             if(pluginClass != null) {
                 instance = pluginClass.CallStatic<AndroidJavaObject>("instance");
                 instance.Call("setContext", activityContext);
                
                 activityContext.Call("runOnUiThread", new AndroidJavaRunnable(() => {
                     instance.Call("LaunchBroadcast");
                 }));
             }
         }
     }

Please help. Pdt: Sorry for the bad english, not my native language