Plesk API - Error - ftp-user not supported

[DennisCitus]

<packet version="1.4.2.0">
<ftp-user>
<get>
   <filter>
      <name>foto2007</name>
   </filter>
</get>
</ftp-user>
</packet>

- Packet version="1.4.2.0">
−
	<ftp-user>
−
	<get>
−
	<result>
<status>error</status>
<errcode>1017</errcode>
<errtext>operator ftp-user is  not supported</errtext>
</result>
</get>
</ftp-user>
</packet>

Request and response.

I have been trying to figure this out for several days now... but have no idea why I still get this error.

The documentation states error 1017 "Feature not supported by Plesk API-RPC.".

Even though I followed the manual according to http://download1.swsoft.com/Plesk/Plesk8.1/Doc/plesk-8.1-api-rpc/35235.htm