title: Mopub ads not showing
body: <p>I've been stuck on an issue for a while and I can't figure out what it is. The thing is I recently updated the <em>Mopub Android SDK</em> and both interstitial + banner ads (<em>AdMob</em> and <em>Millennial Media</em>) were working fine before that. Now these ads aren't working in the release build but they do work in debug build. So I think this is an issue with <code>proguard</code> but I can't trace what it is. The <code>proguard</code> is setup according to <em>Mopub</em> guidelines.</p>
  
  <p>I have added the following to <code>proguard</code> for my project:</p>
  
  <pre><code>-keep class com.google.ads.**
  -keep class com.millennialmedia.android.**
  -keep public class com.mopub.mobileads.*
  -keepclassmembers class com.millennialmedia.android.* {
  public *;
  }
  </code></pre>
  
  <p>In the release build, when I try to display an ad I get the following logs :</p>
  
  <pre><code>I/MoPub   (29856): Fetching ad network type: admob_native
  D/MoPub   (29856): Loading custom event interstitial adapter.
  D/MoPub   (29856): Attempting to invoke custom event: com.mopub.mobileads.GoogleAdMobInterstitial
  D/MoPub   (29856): Couldn't locate or instantiate custom event: com.mopub.mobileads.GoogleAdMobInterstitial.
  
  I/MoPub   (29856): Fetching ad network type: admob_native
  D/MoPub   (29856): Loading custom event adapter.
  D/MoPub   (29856): Attempting to invoke custom event: com.mopub.mobileads.GoogleAdMobBanner
  D/MoPub   (29856): Couldn't locate or instantiate custom event: com.mopub.mobileads.GoogleAdMobBanner.
  V/MoPub   (29856): MoPubErrorCode: Unable to find Native Network or Custom Event adapter.
  </code></pre>
  
  <p>Please suggest what the error might be. Any feedback would be appreciated.</p>
  
  <p>Also I don't know if this is relevant or not but I'm working on a <em>Cocos2dx Android</em> project.</p>
  
  <p>Thanks.</p>