Internal Server Error when unmanaging node over HTTP

Hi,

I am trying to use the Orion SDK to unmanage a node via a http request. My request is as follows:

POST https://10.13.36.29:17778/SolarWinds/InformationService/v3/Json/Invoke/Orion.Nodes/Unmanage HTTP/1.1

Content-Length: 67

Host: 10.13.36.29:17778

Authorization: Basic Q29ubmVjdDpzcG9ydGluZw==

Body:

["N:1114", "2014-03-28T11:55:00Z", "2014-03-28T12:00:00Z", "false"]

And the response I am getting is:

HTTP/1.1 500 Internal Server Error

Content-Length: 275

Content-Type: application/json

Server: Microsoft-HTTPAPI/2.0

Date: Fri, 28 Mar 2014 11:53:18 GMT

"The incoming message has an unexpected message format 'Raw'. The expected message formats for the operation are 'Xml', 'Json'. This can be because a WebContentTypeMapper has not been configured on the binding. See the documentation of WebContentTypeMapper for more details."

Is my request correctly formed and is there somewhere that I can take a look at what the internal server error is?

Thanks,

Kristian