IIS 7 Can you rewrite a rewrite - iis

Question

I am trying to get something like this working with iis 7 microsoft rewrite plugin.
if user requests...
/author/bob/ - show bobs author page
if user requests ...
/author/bob/rss - show authors rss page by rewriting it to
/author/bob/?rss
however i want to to do it in a generic way for urls that end with /rss e.g. for 2 path parts...
<rule name="rss 2 dir listing" stopProcessing="false">
<match url="^([^/]+)/([^/]+)/rss$" />
<action type="Rewrite" url="/{R:1}/{R:2}/?rss" appendQueryString="true" />
</rule>
so the above rule would have to go through to another rewrite rule i.e the one that maps to the author page.
but it looks like this now tries to may to a static directory i.e. the 404 error output is
Requested URL http://site.l:80/author/bob/?rss
Physical Path C:\Users\Workspace\site.l\author\bob\
so its looking for a static directory but you can see its rewritten in to ?rss and trying the url http://site.l:80/author/bob/?rss in the browser works
I am using iis with railo tomcat so it could be a connector issue
Here is the current author rule with the rss incorporated ideally i want to remove adding rss per rule and use generic rules above.
<rule name="author item" stopProcessing="false">
<match url="^author/([a-zA-Z0-9-]+)/(rss)?$" />
<action type="Rewrite" url="/index.cfm?event=AuthorController.getItem&name={R:1}&{R:2}" appendQueryString="true" />
</rule>