[Handbook] Linux 'screen'

there are screens in the list, but "no screen to be resumed" - Unix & Linux Stack Exchange 

Q: there are screens in the list, but "no screen to be resumed"

[root@server chiliNUT]# screen -r
There is a screen on:

27863.pts-1.server (Attached)

There is no screen to be resumed.

A: Use screen -d -r