Incompatible webservice?

I can't seem to get this webservice to work( http://www.maxmind.com/app/minfraud_soap_wsdl5 ), after working out the issue with omit on the optional parameters it is returning the following error:

Cannot perform web service invocation minfraud_soap.
The fault returned when invoking the web service operation is:

AxisFault
faultCode: { http://schemas.xmlsoap.org/soap/envelope/}Server.userException
faultSubcode:
faultString: java.lang.IllegalArgumentException: argument type mismatch
faultActor:
faultNode:
faultDetail:
{ http://xml.apache.org/axis/}stackTrace:java.lang.IllegalArgumentException: argument type mismatch
at org.apache.axis.encoding.ser.BeanPropertyTarget.set(BeanPropertyTarget.java:157)
at org.apache.axis.encoding.DeserializerImpl.valueComplete(DeserializerImpl.java:249)
at org.apache.axis.encoding.DeserializerImpl.endElement(DeserializerImpl.java:509)
at org.apache.axis.encoding.DeserializationContext.endElement(DeserializationContext.java:1087)
at org.apache.axis.message.SAX2EventRecorder.replay(SAX2EventRecorder.java:171)
at org.apache.axis.message.MessageElement.publishToHandler(MessageElement.java:1141)
at org.apache.axis.message.RPCElement.deserialize(RPCElement.java:236)
at org.apache.axis.message.RPCElement.getParams(RPCElement.java:384)
at org.apache.axis.client.Ca... ''

Any ideas?