Trying to activate WP Smush Pro and it's saying "cannot do

Trying to activate WP Smush Pro and it's saying "cannot do this"
Also this came up when I installed the pluggin

WordPress 4.4.1 running WP-DaVinci Premium theme.

Fatal error: Cannot redeclare wp_smush_rating_message() (previously declared in /home3/believe/public_html/wp-content/plugins/wp-smushit/wp-smush.php:73) in /home3/believe/public_html/wp-content/plugins/wp-smush-pro/wp-smush.php on line 88