set default template on custom post

Currently i have a code where i want to set a custom template on custom post and its working fine on my localhost but when i upload it on my host(digitalocean) it just use the single.php

function singlePage_template($template){
    if(is_singular( 'singleProduct' )){
        $template = locate_template(array('single-singleProduct.php'));
    }
    return $template;
}

add_filter('template_include', 'singlePage_template');