Exclude some blog category from blog restriction

Hello!

It’s a very good plugin, realy. But I have a little problem…
I want to exclude a category from blog restriction, and i can’t make it…

I try this code:

function make_category_visible($visibility) {
    global $bp;
    if (in_category(1))
        return false;
    return $visibility;
}

add_filter('pbp_login_required_check', 'make_category_visible');

And I try it with “is_category”, but it’s also wrong… (i’m not a programmer, so it’s isn’t easy for me…)

Can anyone help me?

http://wordpress.org/extend/plugins/private-buddypress/