Can't activate the Revolution slider

This slider came with the thememy client bought. Do you have a solution?

Fatal error: Uncaught Error: [] operator not supported for strings in /home/alamoexteriors/public_html/wp-content/plugins/revslider/includes/framework/base-admin.class.php:69 Stack trace: #0 /home/alamoexteriors/public_html/wp-content/plugins/revslider/admin/revslider-admin.class.php(410): RevSliderBaseAdmin::addMetaBox(‘Revolution Slid…’, ‘’, Array, NULL) #1 /home/alamoexteriors/public_html/wp-content/plugins/revslider/admin/revslider-admin.class.php(69): RevSliderAdmin->addSliderMetaBox() #2 /home/alamoexteriors/public_html/wp-content/plugins/revslider/admin/revslider-admin.class.php(46): RevSliderAdmin->init() #3 /home/alamoexteriors/public_html/wp-content/plugins/revslider/revslider.php(150): RevSliderAdmin->__construct(’/home/alamoexte…’) #4 /home/alamoexteriors/public_html/wp-admin/includes/plugin.php(1882): include(’/home/alamoexte…’) #5 /home/alamoexteriors/public_html/wp-admin/plugins.php(164): plugin_sandbox_scrape(‘revslider/revsl…’) #6 {main} thrown in /home/alamoexteriors/public_html/wp-content/plugins/revslider/includes/framework/base-admin.class.php on line 69

You don’t need to activate the Premium plugins like Slider Revolution or Visual Composer if it comes with WordPress Theme. Theme Author will give you update time to time after theme compatibility testing, also theme author has proper license for their buyer/customer.
Cheers.