Python rauth - do POST requests work?

I have an application that uses python2.7 and rauth to communicate with the etrade api.

Getting the etrade verification token and setting up an authorized session works, and I can successfully execute GET accesses like this:

url = 'https://etwssandbox.etrade.com/accounts/sandbox/rest/accountlist.json'
response  = session.get(url, params = {'format': 'json'}, header_auth=True)

I haven't had any success with POST accesses at all, and despite much searching have yet to find an example that shows the use of post with rauth. I am trying:

url = 'https://etwssandbox.etrade.com/order/sandbox/rest/placeequityorder'

id = datetime.datetime.now().strftime('%y%m%d%H%M')+ticker

payload = {
    "PlaceEquityOrder": {
        "-xmlns": "http://order.etws.etrade.com",
        "EquityOrderRequest": {
            "accountId": account,
            "clientOrderId": id,
            "limitPrice": "",
            "quantity": qty,
            "symbol": ticker,
            "orderAction": "BUY",
            "priceType": "MARKET",
            "marketSession": "REGULAR",
            "orderTerm": "GOOD_FOR_DAY"
        }
    }
}

response = session.post(url, payload, header_auth=True)

and the response I get from etrade is:

{  
   'cookies':<RequestsCookieJar   [  

   ]   >,
   '_content':'<Error>\n  <message>oauth_problem=signature_invalid</message>\n</Error>',
   'headers':{  
      'Content-Length':'69',
      'Expires':'Sat, 21 May 1995 12:00:00 GMT',
      'Keep-Alive':'timeout=60, max=400',
      'apiServerName':'20w44m3',
      'Connection':'Keep-Alive',
      'Pragma':'no-cache',
      'Cache-Control':'no-store, no-cache, must-revalidate, post-check=0, pre-check=0',
      'Date':'Wed, 17 May 2017 15:16:42 GMT',
      'Server':'Apache',
      'WWW-Authenticate':'OAuth realm=https://etws.etrade.com/,oauth_problem=signature_invalid'
   },
   'url':   u'https://etwssandbox.etrade.com/order/sandbox/rest/placeequityorder',
   'status_code':401,
   '_content_consumed':True,
   'encoding':None,
   'request':<PreparedRequest   [  
      POST
   ]   >,
   'connection':<requests.adapters.HTTPAdapter object at 0x7f3187f71790>,
   'elapsed':datetime.timedelta(0,
   0,
   149246   ),
   'raw':<requests.packages.urllib3.response.HTTPResponse object at 0x7f3186c7ab90>,
   'reason':'Unauthorized',
   'history':[  

   ]
}

I'm assuming I'm doing something wrong with the POST request, but is it possible that the rauth library isn't adding the authentication stuff to POST requests?

Well, I didn't get to the bottom of the failing rauth POST requests, but I found an alternative solution.

I'm using the etrade access functions from etradePythonApi (https://github.com/haualan/etradePythonAPI/blob/master/etradepy.py), with the exception that I stripped out the splinter & pyvirtualdisplay code that was attempting to scrape/insert login details into the etrade verification page, and instead replaced it with the oob code from ethann's answer on this page: Getting an oauth request token from etrade in Python

Everything is working nicely using requests directly rather than going via the rauth wrapper, which seems to confirm that POST requests are not getting the Oauth blessing in rauth.

Update: I have made my program available for others to use & adapt at https://github.com/geekbrit/EtradeHotKeys