Tried that already as per 2nd post. Tried with both Json forms. Same error.
As i stated in response to cdecanini_ there is no reason to expect the accept header to work. From here:-
HTTP/1.1: Header Field Definitions
"The Accept request-header field can be used to specify certain media types which are acceptable for the response"
In other words that sets the format of the response coming back from Orchestrator. It does not i believe, tell Orchestrator to accept JSON as the input format.