Asynchronous Interfaces treated as Synchronous one?

Hi eXperts,

I'm now having a weird problem on an Asynchronous inbound interface in a SOAP-XI-R/3 scenario.

When data coming through XI into R/3, the proxy is called, and works fine. But after the proxy call, a short dump happens in CL_PROXY_FRAMEWORK->XI_PROCESS_PAYLOAD saying the payload is 'null'. Since this is an Asynchronous interface, the payload would certainly be 'null' after the proxy call. So the problem is why this method even be called after the proxy?

I checked the stack and found that CALL_PIPELINE_SYNC is used instead of CALL_PIPELINE_ASYNC, and I believe this might be the problem: SAP is treating this as an syschronous interface. However after checking settings in IR, both inbound and outbound interfaces are asynchronous.

Has someone met this before? Does anybody know why SAP is treating an asynchronous interface as a synchronous one?

Thanks in advance for your help.

Regards

Luis