REST API and post requests

I'm trying to copy a build configuration using the rest api.

I'm using the uri

http://teamcity:8111/httpAuth/app/rest/projects

and posting xml

<newProjectDescription name='Project  Name' sourceProjectLocator='id:project2'  copyAllAssociatedSettings='true' shareVCSRoots='false'/>

as per the api.

I however get back a 'unsuspported media type'.

I'm setting the content_type header to 'text/xml'

I have also tried with and without the '<?xml version='1.0'?>

Can you tell me exactly what is required please.