Problem początkującego ze “screen -r x”

Mam problem, jeśli wpisuje "-ls", bo mi nie działa komenda "screen -r x" bo wyskakuje mi

"There is no screen to be resumed matching x" to pokazuje mi się:
No command '-ls' found, did you mean:
 Command 'ls' from package 'coreutils' (main)
 Command 'fls' from package 'sleuthkit' (universe)
 Command 'jls' from package 'sleuthkit' (universe)
 Command 'bls' from package 'bacula-sd' (universe)
 Command 'bls' from package 'bareos-tools' (universe)
 Command 'i-ls' from package 'integrit' (universe)
 Command 'ils' from package 'sleuthkit' (universe)
 Command 'hls' from package 'hfsutils' (main)
 Command 'als' from package 'atool' (universe)
 Command 'ols' from package 'speech-tools' (universe)
-ls: command not found

co mam zrobić..? Ktoś wie?