Can't install Piwik stats

Hello, guys!

I'm having some troubles installing Piwik stats straight from the Applications page in Plesk. The error below pops up, happens to all domains. Any ideas? I'm a little lost.

Error: The following error has occurred during the installation of application: Installation of Piwik at **** failed. Non-zero exit status returned by script. Output stream: 'PHP Fatal error: Uncaught Error: Call to undefined function mysql_connect() in...

Can't install Piwik stats