# Error trying to use Psychophysics toolbox

**URL:** https://psychtoolbox.discourse.group/t/error-trying-to-use-psychophysics-toolbox/314
**Category:** Uncategorized
**Created:** [October 3, 2019, 9:33am UTC](https://psychtoolbox.discourse.group/t/error-trying-to-use-psychophysics-toolbox/314 "2019-10-03T09:33:00Z")
**Posts on this page:** 2
**Page:** 1

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### Author: ![Allen\_Ingling](https://avatars.discourse-cdn.com/v4/letter/a/a183cd/32.png) [@Allen\_Ingling](https://psychtoolbox.discourse.group/u/Allen_Ingling)
#### Post date: [October 3, 2019, 9:33am UTC](https://psychtoolbox.discourse.group/t/error-trying-to-use-psychophysics-toolbox/314/1 "2019-10-03T09:33:00Z")

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Hi

I am a new research student and I am trying to set up Psychophysics toolbox to use for my research.&nbsp; I have MATLAB installed on my laptop and I have tried to download and install the Psychophysics toolbox.&nbsp; I have also download gstreamer.

I can see the directory structure etc. inside MATLAB and following a simple tutorial I have found I tried the following commands with the errors shown-

PsychStartup: Adding path of installed GStreamer runtime to library path. [C:\gstreamer\1.0\x86\_64\bin]

> \>\> cd C:\toolbox  
> \>\> whichScreen=0;  
> \>\> window=Screen(whichScreen,'OpenWindow');

Invalid MEX-file 'C:\toolbox\Psychtoolbox\PsychBasic\MatlabWindowsFilesR2007a\Screen.mexw64': The specified module could not be found.

Any idea what has gone wrong?&nbsp; I have tried to swap these files but still get the error message.

Jim F

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### Author: ![ianzolina](https://avatars.discourse-cdn.com/v4/letter/i/da6949/32.png) [@ianzolina](https://psychtoolbox.discourse.group/u/ianzolina)
#### Post date: [October 4, 2019, 1:49pm UTC](https://psychtoolbox.discourse.group/t/error-trying-to-use-psychophysics-toolbox/314/2 "2019-10-04T13:49:45Z")

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Try to CD into&nbsp;C:\toolbox\Psychtoolbox\ in MATLAB and rerun SetupPsychtoolbox.m — and if you are using a new PTB perhaps you need to reinstall GStreamer as there is now a hard requirement for Windows users for the MSVC version, typing "help GStreamer" tells us that:
  

> > For MS-Windows: 64-Bit Intel MSVC runtime v1.16.0 for use with 64-Bit Matlab/Octave.
> > 
> > &nbsp;
> > 
> > &nbsp; \<https://gstreamer.freedesktop.org/data/pkg/windows/1.16.0/gstreamer-1.0-msvc-x86\_64-1.16.0.msi\>
> > 
> > &nbsp;
> > 
> > &nbsp; You \*must\* install the MSVC variants of GStreamer, not the MinGW64 variants!
> 
> &nbsp;