# Error message at the begining of code **URL:** \ **Category:** Programming Help\ **Tags:** macos\ **Created:** [April 25, 2020, 3:39am UTC](https://psychtoolbox.discourse.group/t/error-message-at-the-begining-of-code/3192 "2020-04-25T03:39:27Z")\ **Posts on this page:** 2\ **Page:** 1
**Author:** ![stag209](https://avatars.discourse-cdn.com/v4/letter/s/eada6e/32.png) [@stag209](https://psychtoolbox.discourse.group/u/stag209)\ **Post date:** [April 25, 2020, 3:39am UTC](https://psychtoolbox.discourse.group/t/error-message-at-the-begining-of-code/3192/1 "2020-04-25T03:39:27Z")
Hello everyone I am new to psychophysics, matlab and psychtoolbox. I have been trying to run an experiment with codes from my project and I keep getting this error message which I dont know how to fix. I use a MacBook Pro, 2019, macOS Catalina version 10.15. and Matlab version R2019b. See the error message: > > AcuityBoost4 > > Unrecognized function or variable ‘DefInput’. Error in AcuityBoostInteractiveChoices (line 6) P.ParticipantID = DefInput(‘Participant ID?’,‘test’); Error in AcuityBoostInit4 (line 6) AcuityBoostInteractiveChoices Error in AcuityBoost4 (line 10) AcuityBoostInit4; so I checked on the error message in AcuityBoostInteractiveChoices- line 6: this is the code on line 6: P.ParticipantID = DefInput(‘Participant ID?’,‘test’); I do not know how to go about it to make modifications so that the experiment can run. I will so much appreciate if someone can point me in the right direction in terms of what to change to make the programme run. Thank you ---
**Author:** ![dcnieho](https://avatars.discourse-cdn.com/v4/letter/d/779978/32.png) [@dcnieho](https://psychtoolbox.discourse.group/u/dcnieho)\ **Post date:** [April 25, 2020, 7:26am UTC](https://psychtoolbox.discourse.group/t/error-message-at-the-begining-of-code/3192/2 "2020-04-25T07:26:54Z")
It appears that you are missing parts of the code. The best step is perhaps to ask the one who wrote it if they can send what is missing, or help in setting it up to run on your machine