libhttp (Scot K) usage question

I'm writing an app using http_req while also testing with soapui. I am getting different results. SoapUI is returning a json while http_req returns blanks (/tmp/lv/a.txt) but show error 36 in the log file.

Is there a way to get the json results into either a.txt or string to receive results?

http_req results
rc = http_req( 'POST'
               : 'https://xx/xx/xx'
               : '/tmp/lv/a.txt'            // File to receive
               : *omit                      // String to receive
               : *omit                      // File to send
               : sndstr                     // String to send
               : 'application/json');

SetError() #13: HTTP/1.1 401
recvresp(): end with 401
recvdoc parms: chunked 0
SetError() #36: This page requires a user-id & password
http_close(): entered

SoapUi results
{
   "code": 400,
   "message": "Invalid credentials"
}