[Trouble shooting] There is a screen on ... When you can't attach on the screen!

Problem)

I turned off by accident my computer without termination.

When I'm trying to log on my screen again, following error appears.

>> screen -r myScreenName

There is a screen on :

15735.myScreenName (Attached)

Solution)

Try detach it first with screen -d <15735> or screen -D <pid>