How to add a new document using the REST API

It would be helpful if there were examples of how to use the REST API.  What I'm trying to do is use Kettle (a ETL product) to automate the storage of documents that we get from customers.  Kettle allows me to use REST, create/read JSON, etc.

I broke my problem down into the following steps and I'm guessing that others have done the same thing as the steps would apply to almost anyone who wants to insert a file into a vault.
[list type=decimal]

• Get the authentication token for a vault by posting to REST/server/authenticationtokens

• Use the returned authtoken to upload a file to the server

[/list]

I've tried to post to /files, http://www.m-files.com/mfws/resources/files.html by following the example given for C# (it's not too hard to transpose the C# example into REST) but I haven't had any luck as I apparently haven't correctly completed the first step.  I get back a auth token and put it in X-Authentication.  The error I get makes me think that although I have logged into the application, I haven't passed the right credentials in to log into the vault?

"{""Status"":401,""URL"":""/files"",
""Method"":""POST"",""Exception"":{""Name"":""UnauthorizedAccessException"",""Message"":""Login to vault failed"",""Stack"":[{""FileName"":"""",""LineNumber"":-1,""ClassName"":""MFWS.RestFilters.SecurityFilter"",""MethodName"":
""TryFilter(RestMethodInfo methodInfo, HttpContext httpContext, LogicContext logicContext)""},
{""FileName"":"""",""LineNumber"":-1,""ClassName"":""MFWS.RestFilters.SecurityFilter"",""MethodName"":
""Filter(RestMethodInfo methodInfo, HttpContext httpContext, LogicContext logicContext, Stream& inputStream)""},
{""FileName"":"""",""LineNumber"":-1,""ClassName"":""MFWS.HttpHandlers.RestHandlerDelegate"",""MethodName"":
""GetObject(HttpContext context)""},{""FileName"":"""",""LineNumber"":-1,""ClassName"":
""MFWS.HttpHandlers.HttpHandler"",""MethodName"":""ProcessRequest(HttpContext context)""}]}
,""Stack"":""   
at MFWS.RestFilters.SecurityFilter.TryFilter(RestMethodInfo methodInfo, HttpContext httpContext, LogicContext logicContext)\r\n   
at MFWS.RestFilters.SecurityFilter.Filter(RestMethodInfo methodInfo, HttpContext httpContext, LogicContext logicContext, Stream& inputStream)\r\n   
at MFWS.HttpHandlers.RestHandlerDelegate.GetObject(HttpContext context)\r\n   
at MFWS.HttpHandlers.HttpHandler.ProcessRequest(HttpContext context)\r\n"",""Message"":""Login to vault failed"",""IsLoggedToVault"":false,""IsLoggedToApplication"":true}"