Slider – Plugin could not be activated because it triggered a fatal error

Hello,

Purchased the fortuna theme last week, very pleased with all I have seen of it so far….
One issue:
When I try to activate the Revolution Slider plugin I get the above error. The complete error message is…..

Fatal error: Uncaught Error: [] operator not supported for strings in /home/588/346588/public_html/wp-content/plugins/revslider/includes/framework/base-admin.class.php:71 Stack trace: #0 /home/588/346588/public_html/wp-content/plugins/revslider/admin/revslider-admin.class.php(572): RevSliderBaseAdmin::addMetaBox(‘Revolution Slid…’, ”, Array, NULL) #1 /home/588/346588/public_html/wp-content/plugins/revslider/admin/revslider-admin.class.php(73): RevSliderAdmin->addSliderMetaBox() #2 /home/588/346588/public_html/wp-content/plugins/revslider/admin/revslider-admin.class.php(44): RevSliderAdmin->init() #3 /home/588/346588/public_html/wp-content/plugins/revslider/revslider.php(162): RevSliderAdmin->__construct(‘/home/588/34658…’) #4 /home/588/346588/public_html/wp-admin/includes/plugin.php(1882): include(‘/home/588/34658…’) #5 /home/588/346588/public_html/wp-admin/plugins.php(164): plugin_sandbox_scrape(‘revslider/revsl…’) #6 {main} thrown in /home/588/346588/public_html/wp-content/plugins/revslider/includes/framework/base-admin.class.php on line 71

Any help / suggestions would be much appreciated

Thanks