DW Q&A pro activity problem

When I try to activate dw, I get the following error:

Warning: Illegal string offset ‘sv/0’ in /customers/4/2/d/allofthemcasinos.com/httpd.www/wp-content/plugins/sitepress-multilingual-cms/sitepress.class.php on line 9003 Warning: Cannot assign an empty string to a string offset in /customers/4/2/d/allofthemcasinos.com/httpd.www/wp-content/plugins/sitepress-multilingual-cms/sitepress.class.php on line 9003 Fatal error: Uncaught Error: Cannot unset string offsets in /customers/4/2/d/allofthemcasinos.com/httpd.www/wp-content/plugins/sitepress-multilingual-cms/sitepress.class.php:9004 Stack trace: #0 /customers/4/2/d/allofthemcasinos.com/httpd.www/wp-includes/class-wp-hook.php(288): SitePress->rewrite_rules_filter(”) #1 /customers/4/2/d/allofthemcasinos.com/httpd.www/wp-includes/plugin.php(208): WP_Hook->apply_filters(”, Array) #2 /customers/4/2/d/allofthemcasinos.com/httpd.www/wp-includes/option.php(152): apply_filters(‘option_rewrite_…’, ”, ‘rewrite_rules’) #3 /customers/4/2/d/allofthemcasinos.com/httpd.www/wp-includes/option.php(307): get_option(‘rewrite_rules’) #4 /customers/4/2/d/allofthemcasinos.com/httpd.www/wp-includes/class-wp-rewrite.php(1804): update_option(‘rewrite_rules’, ”) #5 /customers/4/2/d/allofthemcasinos.com/httpd.www/wp-includes/rewrite.php(276): WP_Rewrite->flush_rules(true) #6 /customers/4/2/d/allofthemcasinos.com/httpd.www/wp-content/plugins/dw-question-answer-pro/dw-question-answer.php(255): flus in /customers/4/2/d/allofthemcasinos.com/httpd.www/wp-content/plugins/sitepress-multilingual-cms/sitepress.class.php on line 9004