populate a dropdownlist calling a webservice with jQuery

Hi people, I have a code and it won't work, I can't figure out what I'm doing wrong, here is my code:

the webservice:1 namespace UnifluWeb
2 {
3 [WebService(Namespace = "http://tempuri.org")]
4 [WebServiceBinding(ConformsTo = WsiProfiles.BasicProfile1_1)]
5 [System.ComponentModel.ToolboxItem(false)]
6 [ScriptService]
7 public class UnifluWeb : System.Web.Services.WebService
8 {
9 [WebMethod]
10 [ScriptMethod(ResponseFormat = ResponseFormat.Json)]
11 public List<Cidade> CidadePorUF(long UFID)
12 {
1 ...