如何将{name：value}对与Gorilla Mux HandleFunc配合使用？

I use a mux router with a function handler

r := mux.NewRouter()
r.HandleFunc("/test/{myfirst}/{mysecond}/{third:[0-9]+}",TestHandler)

The test handler is defined as follows:

func TestHandler(response http.ResponseWriter, request *http.Request) {
    response.Header().Set("Content-type", "text/html")
    err := request.ParseForm()
    if err != nil {
        http.Error(response, fmt.Sprintf("error parsing url %v", err), 500)
    }
    vars := mux.Vars(request)
    first := vars["myfirst"]
    second := vars["mysecond"]
    third := vars["mythird"]
}

I call the page with

http://localhost/test/first/second/third/1234

But I get a 404. Also third:value didn't work. What is the right url? And can I retrieve vars of a name/value pair like this?