IDE: Android Studio 0.3.5

android:minSdkVersion="7"

android:targetSdkVersion="19"

GoogleAdMobAdsSdk 6.4.1

Error: 10-07 07:54:00.693    2588-2588/package I/Ads﹕ onFailedToReceiveAd(Invalid Ad request.)

Solution:
get a corret  MY_AD_UNIT_ID!

go to https://apps.admob.com/ (more exactly https://apps.admob.com/?pli=1#monetize/app:view/id=APP_ID )

Gel all ID "ca-app-xxxxxxxxxxxxxxxxxxxxxxx"

put in yout layout.xml

[geshi]

<com.google.ads.AdView android:id="@+id/adView"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
ads:adUnitId="ca-app-pub-xxxxxxxxxxxxxxxxxxxxxx"
ads:adSize="BANNER"
ads:testDevices="TEST_EMULATOR"
ads:loadAdOnCreate="true"/>

[/geshi]

Clean and run your project!

Be happy :)