issue activating prosites plugin

Hi,
i have this message error when activating prosites:
Parse error: syntax error, unexpected T_PAAMAYIM_NEKUDOTAYIM in /home/www/tn-mailer.com/wp-content/plugins/pro-sites/pro-sites-files/lib/ProSites/Module/Taxamo/lib/Taxamo/Swagger.php on line 185

Thanks