Multiple supervisor in Groups

Hi,

When I try to add multiple supervisor for one group in AP, It throws an error of UNKNOWN_SUPERVISOR.

Output logs:-

##supervisor XML<supervisors xsi:type="m:SoapSupervisorList"><supervisor xsi:type="m:SoapSupervisor"><name xsi:type="xsd:string">501634916</name></supervisor></supervisors><supervisors xsi:type="m:SoapSupervisorList"><supervisor xsi:type="m:SoapSupervisor"><name xsi:type="xsd:string">502002487</name></supervisor></supervisors>

SoapResponse:-

soapResponse: <?xml version='1.0' encoding='UTF-8'?><soapenv:Envelope xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/"><soapenv:Body><ns:AddGroupResponse xmlns:ns="http://www.alarmpoint.com/webservices/schema"><ns:return type="com.invoqsystems.apex.web.soap.AddGroupReturn"><ns:serverTimestamp>18/01/2013 12:44:19 PM</ns:serverTimestamp><ns:status>UNKNOWN_SUPERVISOR</ns:status></ns:return></ns:AddGroupResponse></soapenv:Body></soapenv:Envelope>

Kindly help me in searching the reason for this error.

Thanks,

Swity Patel.