iis7.5 isapi dll no general_response_header

Hi,

I have a very strange issue that I am unable to resolve.

ISAPI DLL works on IIS5.5. Recently migrate it to IIS7.5 and I am setting some stange results.

The same DLL is called for a specific COM+ object.

All function calls returns with General_Response_Header except one. It only returns the GENERAL_RESPONSE_ENTITY_BUFFER without the field GENERAL_RESPONSE_HEADERS. 

Is this a setting with IIS that strips out response headers? What options/troubleshooting do I have to see what might have cause this issue?

thanks

Frank