Int32 must be serializable

[Greg]

I have an orchestration which consumes a web service. The web methods
all have a similar signature, i.e. public int
MyMethod(List<ComplexType> myList)

Using BizTalk 2006, the complier is throwing the following error;

'System.Int32' must be Xml serializable to be a message part type

And flags the error in the web service orchestration reference document
(Reference.odx) in the WebPortBinding section ...

module MyOrchestrations.InterfaceService.InterfaceService_
{

[Microsoft.XLANGs.BaseTypes.WebPortBinding(typeof(MyOrchestrations.InterfaceService.InterfaceService),
"MyMethod", Microsoft.XLANGs.BaseTypes.EXLangSMessageInfo.eRequest)]
public messagetype MyMethod_request
{
body
MyOrchestrations.InterfaceService.Reference.ArrayOfComplexTypeTO
checkArray;
};

[Microsoft.XLANGs.BaseTypes.WebPortBinding(typeof(MyOrchestrations.InterfaceService.InterfaceService),
"MyMethod", Microsoft.XLANGs.BaseTypes.EXLangSMessageInfo.eResponse)]
public messagetype MyMethod_response
{
body System.Int32 MyMethodResult; ****** ERROR FLAGGED HERE
*******
};

Given that System.Int32 is serializable, any ideas whats causing this
error?

(I have noticed that BTS2006 error messages are sometimes way off
what's actually wrong, but that's another issue!)

Greg.

[Greg]

Back into work this morning, and all appears fine after a reboot!

Greg.