mock service with query parameter is not working.

I have created a mock service "/CreateItem/{detailsjson}" and  using below dispatcher script I am returning the request text as response (for sample test purpose)

def queryString = mockRequest.getRequest().getQueryString()
log.info "QueryString: " + queryString
return queryString

But when I invoke the mock service from test suite I get 404 error. Any idea what could be the problem.