manifest version number effects Facebook login?

manifest version number effects Facebook login?

In order to update my app in Google play store I had to change my version
number in the Android manifest. I updated the file from:
android:versionCode="1"
android:versionName="1.0"
to:
android:versionCode="2"
android:versionName="2.0"
the market accepted the new apk, but Facebook log in dialog stopped
showing! each time the dialog started loading it immediately close before
the user can input his username and password. Integrated Facebook app log
in stopped working as well.
I couldn't find anything in stackoverflow/google about this, what did I do
wrong?
Thank you!!