When trying to install the latest version of Concrete5 (8.1.0), all pre-installation requirements check out O.K. but then then I get the ERROR:

{"error":{"message":"Call to undefined function Doctrine\\Common\\Annotations\\token_get_all()"},"errors":["Call to undefined function Doctrine\\Common\\Annotations\\token_get_all()"]}

Any ideas as to what is going wrong here? This has been my typical experience with C5... Everything looks so great on paper and in the videos until installation. Then it all falls apart.

I have PHP version 5.6.13 , MySQL 5.5.28 (these meet requirements)
Zend Engine v2.6.0
cURL 7.28.0 - enabled
DOM - enabled
SimpleXML - enabled
fileinfo - enabled
Mbstring - enabled
Mcrypt - enabled