Maps Android V2: java.lang.noclassdeffounderror: com.google.android.gms.R$styleable

Maps Android V2: java.lang.noclassdeffounderror:
com.google.android.gms.R$styleable

As many I get the following error: java.lang.noclassdeffounderror:
com.google.android.gms.R$styleable when trying to implement Maps for
Android V2.
Somehow I must be missing what I exactly am doing wrong, since it's not
working. What I tried first is to copy the google-play-services.lib into
the lib folder, but I saw somewhere I shouldn't do this.
Then I tried to import addon-google_apis-google-8 as a project, but the
project gives the error The import com.google cannot be resolved.
I'm following the Vogella Tutorial:
Activity:
SupportMapFragment fm = (SupportMapFragment)
getSupportFragmentManager().findFragmentById(R.id.map);
map = fm.getMap();
//map = ((MapFragment)
getFragmentManager().findFragmentById(R.id.map)).getMap();
Marker hamburg = map.addMarker(new
MarkerOptions().position(HAMBURG)
.title("Hamburg"));
Marker kiel = map.addMarker(new MarkerOptions()
.position(KIEL)
.title("Kiel")
.snippet("Kiel is cool")
.icon(BitmapDescriptorFactory
.fromResource(R.drawable.btn_logo)));
// Move the camera instantly to hamburg with a zoom of 15.
map.moveCamera(CameraUpdateFactory.newLatLngZoom(HAMBURG,
15));
// Zoom in, animating the camera.
map.animateCamera(CameraUpdateFactory.zoomTo(10), 2000,
null);
Manifest:
<uses-sdk
android:minSdkVersion="8"
android:targetSdkVersion="17" />
<permission
android:name="com.testmap.test.permission.MAPS_RECEIVE"
android:protectionLevel="signature" />
<uses-permission
android:name="com.testmap.test.permission.MAPS_RECEIVE" />
<uses-permission
android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
<uses-permission
android:name="com.google.android.providers.gsf.permission.READ_GSERVICES"
/>
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION"/>
<uses-permission
android:name="android.permission.ACCESS_COARSE_LOCATION"/>
<uses-permission android:name="android.permission.WRITE_SETTINGS" />
uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
<uses-feature
android:glEsVersion="0x00020000"
android:required="true" />
<meta-data
android:name="com.google.android.maps.v2.API_KEY"
android:value="a_real_api_key" />
</application>
I retrieved a_real_api_key by entering the SHA1 retrieved by installing
the keytool plugin.. http://keytool.sourceforge.net/update
fingerprint;com.testmap.test in the google console.
And xml:
<fragment
android:id="@+id/map"
android:layout_width="match_parent"
android:layout_height="match_parent"
class="com.google.android.gms.maps.SupportMapFragment" />
I have the feeling I need to import the google-play-services library, can
somebody tell me step by step how to do this in Eclipse, I've followed
many answers, but I seem to do something wrong every time.