passed a paramter in Rest URL, but results returned are wrong!

Hi
I am making a rest submission to a restful server as follows:
<xforms:submission
                                id="sub-get-data"
                                action="http://localhost:9001/restfulserver/XmlIntercept/lists/Hairpath?q={instance('DataResponse')/fe:q}"
                                method="get"
                                replace="instance"
                                instance="Response"/>

in the instance I have
<xforms:instance id="DataResponse">
                <fe:xx>
                   <fe:departmentID/>
                                                         <fe:q>for%20$p%20in%20//item%20where%20contains($p,%20%ORANGE%22)%20return%20$p</fe:q>
                                </fe:xx>
         </xforms:instance>

The server returns XML on  action="http://localhost:9001/SimpleXmlServer/XmlIntercept/lists/Hairpath" and I am trying to filter out the results by passing a parameter and I expect to get back a smaller subset of the XML, but instead I am getting back the full XML. So no filtering is happening.

Any suggestions are appreciated.