The console function might be disabled. 

Please use the following commands ro enable the console.

Enable Local (LCD) console; Disable 2nd console or external console video 

-> [Ctrl] [Alt] [Shift] [L] [Enter] 

Enable 2nd console, or external console video; Disable Local (LCD) console.

-> [Ctrl] [Alt] [Shift] [R] [Enter]

Enable both consoles (default)

-> [Ctrl] [Alt] [Shift] [L] [R] [Enter] or [Ctrl] [Alt] [Shift] [R] [L] [Enter]