Weird Image display problem

[mickers]

Hi all,
I have a strange problem, and I'm trying to isolate it. I have an accelerator setup like this

(browser)-> https://ichain.address/path/file.cfm -> (server)http://IIS.server/path/file.cfm
The file.cfm actually returns an image (eg jpeg) mimetype (see below). If I try http://IIS.server/path/file.cfm I see the image fine. This is returned

HTTP/1.1 200 OK
Connection: close
Date: Mon, 02 Jun 2008 05:00:45 GMT
Server: Microsoft-IIS/6.0
Content-Language: en-AU
Content-Type: image/jpeg

If I try through ichain I get an error (box with 'x' in the middle) and

HTTP/1.1 200 OK
Date: Mon, 02 Jun 2008 05:02:20 GMT
Server: Microsoft-IIS/6.0
Content-Language: en-AU
Content-Type: image/jpeg
Connection: close
Content-Length: 4
Cache-Control: no-store
Cache-Control: no-cache
Pragma: no-cache
Via: 1.1 ics_server.our.address (iChain 2.3.347)

Is there something I'm missing? I've been banging my head, and I'm not sure if the problem lies with iChain or the 3rd party app.

Cheers.