I'm receiving this error message when trying to create a HOST user in the sandbox site.
 
<?xml version="1.0" encoding="utf-16"?>
<serv:message xmlns:use="http://www.webex.com/schemas/2002/06/service/user" xmlns:att="http://www.webex.com/schemas/2002/06/service/attendee" xmlns:meet="http://www.webex.com/schemas/2002/06/service/meeting" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:serv="http://www.webex.com/schemas/2002/06/service">
  <serv:header>
    <serv:securityContext>
      <use:webExID>******</use:webExID>
      <use:password>******</use:password>
      <use:siteID>******</use:siteID>
      <use:partnerID>******</use:partnerID>
    </serv:securityContext>
  </serv:header>
  <serv:body>
    <serv:bodyContent xsi:type="use:createUser">
      <use:firstName>First</use:firstName>
      <use:lastName>Last</use:lastName>
      <use:webExId>userwebexid</use:webExId>
      <use:email>user@mail.com</use:email>
      <use:password>******</use:password>
      <use:timeZoneID>0</use:timeZoneID>
      <use:privilege>
        <use:host>true</use:host>
      </use:privilege>
      <use:active>ACTIVATED</use:active>
      <use:personalMeetingRoom>
        <use:welcomeMessage>Welcome</use:welcomeMessage>
      </use:personalMeetingRoom>
      <use:sessionOptions>
        <use:defaultSessionType>100</use:defaultSessionType>
        <use:defaultServiceType>EventCenter</use:defaultServiceType>
        <use:autoDeleteAfterMeetingEnd>false</use:autoDeleteAfterMeetingEnd>
        <use:displayQuickStartHost>true</use:displayQuickStartHost>
        <use:displayQuickStartAttendees>false</use:displayQuickStartAttendees>
      </use:sessionOptions>
      <use:salesCenter>
        <use:roles />
        <use:smeInfo>
          <use:products />
        </use:smeInfo>
      </use:salesCenter>
    </serv:bodyContent>
  </serv:body>
</serv:message>

 
The same occur if I try to create a less privileges account (using "attendeeOnly" instad of "host" in privilege). Maybe the problem is that I'm not able to create users in the sandbox site? Or perhaps I'm doing something else wrong?
 
Thanks in advance