UPnP Server Error 501

[Franz Edler]

Is there any chance to find out what is the cause of the error below?
This is the answer of my Windows XP pro on a AddPortMapping-Command.


HTTP/1.0 500 Internal Server Error
Date: Thu, 25 Dec 2003 14:18:26 GMT
Connection: close
Server: Microsoft-Windows-NT/5.1 UPnP/1.0 UPnP-Device-Host/1.0
Content-Length: 503
Content-Type: text/xml; charset="utf-8"
EXT:

<?xml version="1.0"?>
<SOAP-ENV:Envelope xmlns:SOAP-
ENV="http://schemas.xmlsoap.org/soap/envelope/"
SOAP-
ENV:encodingStyle="http://schemas.xmlsoap.org/soap/encodin
g/">
<SOAP-ENV:Body>
<SOAP-ENV:Fault>
<faultcode>SOAP-ENV:Client</faultcode>
<faultstring>UPnPError</faultstring>
<detail>
<UPnPError xmlns="urn:schemas-upnp-org:control-1-0">
<errorCode xmlns="">501</errorCode>
<errorDescription xmlns="">Action Failed</errorDescription>
</UPnPError>
</detail>
</SOAP-ENV:Fault>
</SOAP-ENV:Body>
</SOAP-ENV:Envelope>