After having trouble getting the facebook login to work, i’ve finally found the solution. I thought it might be helpfull for others, so i share it here.
When you are working on a Windows7 64bit computer you have to generate the key hashes with the x64 version of Openssl, otherwise the hashes won’t work.
Found the solution here: http://stackoverflow.com/questions/4388992/key-hash-for-android-facebook-app