WSDL to call web service responded but returned nothing

Hi all,

Provided wsdl from link below:

http://www.2shared.com/file/zfTUDRl3/poccrm.html

I've been given merely a wsdl above from client, without any further information given, to make a call using c# code but i added as web reference, used the codes below and the client side detected my request and they've returned us proper format xml too, but i cant retrieve it in the string array from the method returned. the "stringset" has became null instead of array[10]. Can anyone give a hint what kind of web service call is it, since it is not using the simple and classic way to invoke?Thanks for help~

static void Main(string[] args)
{
//added web reference for wsdl as poccrm
string[] stringset = new string[10];
poccrm.poclib caller = new ConsoleApplication1.poccrm.poclib();
poccrm.SE1I2001 callerItem = new poccrm.SE1I2001();
callerItem.AcctNo = "0010241000007914";
callerItem.TransNo = "12345678901234567890";
callerItem.StartDate = "20-01-2010";
stringset = caller.SE1I2001(callerItem); //here i get null for stringset, but client received the request and returned us value

//same result even I use wsdl.exe converted it to a class file
/*
string[] stringset = new string[10];
poclib caller = new poclib();
SU1I1001 callerItem = new SU1I1001();
callerItem.AcctNo = "0010029004000370";
callerItem.transno = "12345678901234567890";
caller.end
stringset = caller.SU1I1001(callerItem);
*/

}