lasca on "[Plugin: W3 Total Cache] Plugin could not be activated because it triggered a fatal error"

I tried to install plugin and got this error message

Fatal error: Call to undefined function w3tc_button_link() in /home/uu02/public_html/wp-content/plugins/w3-total-cache/lib/W3/GenericAdminEnvironment.php on line 99

My site is http://uniquelyus.co.za/

http://wordpress.org/plugins/w3-total-cache/