[avatar] Shortcode does not work

Hi I’m trying to use the [avatar] shortcode in a front-end user dashboard. I’ve uploaded my avatar but the dashboard picture still shows the mystery man.

Here’s the code that I have:

function ss_get_current_avatar(){
    $user = wp_get_current_user();
    echo get_avatar($user->ID, 96);
}

function add_gravatar_class($class) {
    $class = str_replace('class="avatar', 'class="avatar welcome_avatar', $class);
    return $class;
}

Am I doing something wrong? Thanks in advanced.

https://ww.wp.xz.cn/plugins/wp-user-avatar/