IBM Connections - can't add opensocial gadget

I developed an open social gadget and am trying to display it in Connections. I can't get Connections to even try to load the xml definition file.

I get "Unable to load widget" in the gadget area in the side column

In JS console the errors read:

(Usable to retrieve spec for gadgeturl. HTTP error 400) while loading widget

_WidgetHandleBase - gadget failed to load (gadgeturl)

Here's what I did:

1) Enabled developer mode and restarted Connections. I used this guide as a reference, allServers attribute is set to true so I'm not using the whitelist. http://public.dhe.ibm.com/software/dw/lotus/OS_gadget_IC4_final.pdf

2) Configured the gadget in admin section of Connections.

• Type: Open Social Gadget
• Security: Trusted, Use SSO
• Server Access via Proxy: All Servers
• Display on the Widgets page: True
• Display on the Updates page: True
• Use IBM Connections specific tags: True
• Opened by default: True

3) Added the gadget through the customize link

Again, the gadget url leads to an xml definition file and it is accessible via a browser. Connections never accessed the url based on server logs.

Any idea what I am missing?

Thanks, Vilem

Based on Paul Bastide's questions I did these additional steps:

• In opensocial-config.xml I set all whitelistEnabled and urlWhitelistEnabled attributes to false. Setting up just the developer tag attributes like the doc suggested wasn't enough.
• Set up hosts file to allow the connections server to access the gadget url.

For clarity I am using the Greenhouse image.