Invalid IL code in (wrapper runtime-invoke)

[Andrus]

In Mono 2.4. Calling ASMX web method

[WebMethod()]
 public string AddNew(ref UserCredentials header, string headerEntity,
                        List<FormField> headerFields, List<RidT> rowFields)
{ ...


Returns exception

 <soap:Body>
 <soap:Fault>
  <faultcode>soap:Server</faultcode>
 <faultstring>Invalid IL code in (wrapper runtime-invoke)
Service.StockService:runtime_invoke_string__this___UserCredentials&_string_List`1<FormField>_List`1<RidT>
(object,intptr,intptr,intptr): IL_002c: call 0x00000004</faultstring>
 </soap:Fault>
</soap:Body>
</soap:Envelope>

How to fix ?

Andrus.

FreeBSD mono.test.com 7.1-PRERELEASE FreeBSD 7.1-PRERELEASE #0: Thu Aug 28 
16:53:13 EEST 2008     dxxh at test.com:/usr/obj/usr/src/sys/ELK  amd64