Quoting Streets of Boston from his adt-dev post:
When upgrading, the ‘Order and Export’ of the new ‘Android Private
Libraries’ is not always checked. And the android-support-v4.jar is now in
this ‘Android Private Libraries’ section.To fix this, go to ‘Order and Export’ and check ‘Android Private
Libraries’. Then refresh/clean/rebuild.After you done this ‘fix’ for a library project, you may need to just close
and re-open any depending project, because they may not see this ‘fix’
immediately.
Give this a shot and with luck it will solve your problem.
