Nginx Routing to Upstream Based on Cookie or Header Value

Question

This one is bugging me and it should work but I must be missing a nuance somewhere:

    #== UPSTREAMS ==
upstream server_vip {
    server superduper.com:443;
}

upstream server_alt_vip {
    server superduper2.com:443;
} 

    map $cookie_route_parallel $pool { 
        default "server_vip";
        value2 "server_alt_vip";
        value1 "server_vip";
    }

        location /directory {
            proxy_pass https://$pool/directory;

It does not appear to be picking up the cookie value.