There could be two things.
i) Make sure you have defined all of your Activity classes in AndroidManifest.xml class.
ii) Make sure you are compiling your Android project using "Google APIs" instead of "Android 2.x", If you compile using Google APIs only then It will add Google Maps classes.
<uses-library android:required="true" android:name="com.google.android.maps" />
<application
android:hardwareAccelerated="true"
android:icon="@drawable/ic_launcher"
android:label="@string/app_name" >
<uses-library
android:name="com.google.android.maps"
android:required="true" />
<activity ...