I installed wordpress 3.8.1 on GAE - transfered from a WP-MU installation on another host. I installed GAE plugin which is working but mentions I should also install batcache and memcached plugins. So I installed them both but they don't seem to be working- I get no debug output in `<head>` section, response is 200 and site is generally slow. What can I do to enable caching? Here are the response headers after 2 reloads with `curl -i`:

```
HTTP/1.1 200 OK
Vary: Cookie
X-Pingback: http://www.websiteinquestion.com/xmlrpc.php
Content-type: text/html; charset=UTF-8
Vary: Accept-Encoding
Date: Sun, 09 Feb 2014 23:20:32 GMT
Server: Google Frontend
Cache-Control: private
Alternate-Protocol: 80:quic,80:quic
Transfer-Encoding: chunked

```

There is some debug output when enabled:

```
Notice: Undefined offset: 1 in /base/data/home/apps/s~xxx/xxx.stringofnumbers/wordpress/wp-content/object-cache.php on line 374

```

Here is the app.yaml

```
application: xxxxx
version: xxx
runtime: php
threadsafe: no
default_expiration: "2d"
api_version: 1
instance_class: F1
automatic_scaling:
  min_idle_instances: 0
  max_idle_instances: 1
  min_pending_latency: automatic
  max_pending_latency: 15000ms

```

in wp-config.php I added 

```
define('WP_CACHE', true);

```

I tried viewing the memcache stats on GAE console but I can't find the viewer anywhere. In settings memcache is set to shared mode.