Hello, I am using official android facebook SDK (downloaded from here: http://github.com/facebook/facebook-android-sdk). When the program reaches the line Facebook facebook = new Facebook(); i get "java.lang.NoClassDefFoundError: com.facebook.android.Facebook". I created a facebook project from sources downloaded and in my project I added the facebook project in buildpath (in Eclipse right click on my project -> Properties -> Java build path -> Projects -> add projects -> I choosed the facebook project). The project builds ok, I have no errors. Any suggestions? Thank you all.