Where's the file pst-arrows?

I'm trying to compile an image done with pstricks but everytime I run it I get the message "I can't find the file 'pst-arrow. ...rrowLoaded\endinput\else\input pst-arrow'"

The thing is... a long time ago I run this code and it was fine. Now I have to modify it but this message keep showing up. And I did not even change anything. I used the pstrick-add package. Thought this would be enough.

I'm using texmaker with MikTex 2.9. Can somebody help me?

Thank you.

Example:

\documentclass{article}

\textheight=25cm
\pagestyle{empty}

\begin{document}

\psset{arrowscale=3}

% Lines (\psline macro)

\begin{pspicture}(2,1)
\psline[ArrowInside=->]{<->}(2,1)
\end{pspicture}

\end{document}

• How are you loading pst-arrow? Are you only loading pstricks-add? Please provide a minimal example that replicates the current erroneous behaviour. Note that there was a recent change in terms of pst-arrow. All the arrow-related code was removed from pstricks-add. – Werner Sep 13 '16 at 20:22
• I included \usepackage{pst-arrow} and still nothing. Do you have any idea where in the miktek file should the arrow.sty be? – Gabu Sep 13 '16 at 20:34

As @Werner pointed in his comment, there has been a recent change in the organisation of pstricks-add. You should install pst-arrow via MiKTeX Package Manager. Don't forget to synchronise the Package Repository first:
• Go to Package Repository and ask to Synchronise to update the database of packages. Probably also launch the Update manager. – Bernard Sep 13 '16 at 20:47