I upgraded to a new rMBP 15" and did a clean install, everything is fine but iMessage. In the preferences it says that the account is (inactive) although it's enabled and everything, handoff is working even with messages although I can't send or receive messages on the MBP. I tried lots of things with no luck, signing out of iMessage on the laptop, signing out of iMessages from my iPhone, iPad and Laptop, signing out of iCloud account. Still it's always (inactive) and I can't even remove it using the "-" sign at the bottom cause it's greyed out. Any idea how can I get it working?