unexpected T_OBJECT_OPERATOR when trying to connect

[php-surfer]

Apologies if this is a really simple problem but I have been trying to get this working for days and haven't been able to get past this hurdle. I have followed the setup instructions @ https://github.com/rileydutton/Exchange-Web-Services-for-PHP and when I run the test code on that page to send a simple email I get the below error

Parse error: syntax error, unexpected T_OBJECT_OPERATOR in C:\inetpub\wwwroot_Includes\EWS\lib\ExchangeClient.php on line 583

Any ideas?