Error on screen function using psychtoolbox 3 on matlab

Hi everybody
I am using acer travel mate p corei5 windows 11 PC and I have this issue on Matlab when running Psychtoolbox 3:

Unrecognized function or variable ‘Screen’.

Error in TloadDback_Training_Pretest (line 66)
Screen(‘Preference’, ‘Verbosity’, 2); % Output for critical errors and warnings

You have not installed psychtoolbox correctly. Please follow the installation instructions on the website