PHP gzipping JSON, saving to memcache... Node.js serving - proper headers?

In PHP I am doing something like:

$gzdata = gzencode(json_encode($data), 9);
$mc->set("latest", $gzdata);

So I pull my associative array from the DB, I turn it to JSON, Gzip it and store to memcache

In my Node.js I read the memcached entry and serve it (where client is memcache client)

client.get('latest', function(err, response) {
            if (err) { console.log("GET", err.type ); } 
            else{
                result.writeHead(200,{
                    "Content-Type": "application/json",
                    "content-encoding":"gzip"
                });


                result.end(response['latest']);
            }
        });

I am getting

Content Encoding Error

on the page

The page you are trying to view cannot be shown because it uses an invalid or unsupported form of compression.

I cannot even check the headers in FB... any ideas what am I doing wrong?