error network activating pro sites

When I attempted to network activate, I got the following error:

Parse error: syntax error, unexpected T_PAAMAYIM_NEKUDOTAYIM in /home/zoe/public_html/bizcards/wp-content/plugins/pro-sites/pro-sites-files/lib/ProSites/Module/Taxamo/lib/Taxamo/Swagger.php on line 185