Web api cors preflight option request returns 200 ok, but doesn't continues to request.

I add cors to my web api application, here's my code: 

[AttributeUsage(AttributeTargets.Method | AttributeTargets.Class, AllowMultiple = false)]
    public class CorsPolicyAttribute : System.Attribute, ICorsPolicyProvider
    {
        private CorsPolicy _policy;

        public CorsPolicyAttribute()
        {
            _policy = new CorsPolicy
            {
                AllowAnyMethod = true,
                AllowAnyHeader = true
            };

            ////_policy.Origins.Add("http://www.example.com");
            var corsOrigins = ConfigHelper.GetAppSettingValue(AttributeConfig.CorsOrigins);
            if (corsOrigins != null)
            {
                if (corsOrigins.Trim() == "*")
                {
                    _policy.AllowAnyOrigin = true;
                }
                else if (string.IsNullOrEmpty(corsOrigins.Trim()))
                {
                    var origins = corsOrigins.Split(new char[] { ',' }, StringSplitOptions.RemoveEmptyEntries);
                    foreach (var origin in origins)
                    {
                        _policy.Origins.Add(origin);
                    }
                }
            }
        }

        public Task<CorsPolicy> GetCorsPolicyAsync(HttpRequestMessage request, System.Threading.CancellationToken cancellationToken)
        {
            return Task.FromResult(_policy);
        }
    }

And add this attribute to my controller.

The WebApiConfig.cs

public static void Register(HttpConfiguration config)
        {
            config.EnableCors();

            config.MapHttpAttributeRoutes();

            config.Routes.MapHttpRoute(
                name: "DefaultApi",
                routeTemplate: "api/{controller}/{id}",
                defaults: new { id = RouteParameter.Optional }
            );
        }

I need to add some authorization data in headers, here's my code by javascript with jquery:

var urls = "http://192.168.0.133/AuthorizationService/api/Auth";
var deviceId = "";$.ajax(urls, {
type: 'post',
data: {
 UserName: $("#userName").val(),
 Password: $("#password").val(),
 Token: "",
 DeviceId: deviceId
},

headers: {
 AuthorizationToken: "adac4d7f6d4b78952ddb3b02ccd85434",
 Authorizationkey: "key"
},
success: function(data) {...

The brower will run a preflight option request. here is my preflight request and response.

Request: 

OPTIONS http://192.168.0.133/AuthorizationService/api/Auth HTTP/1.1
Host: 192.168.0.133
Connection: keep-alive
Access-Control-Request-Method: POST
Origin: http://localhost:33202
User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/43.0.2357.130 Safari/537.36
Access-Control-Request-Headers: accept, authorizationkey, authorizationtoken, content-type
Accept: */*
Referer: http://localhost:33202/login.html
Accept-Encoding: gzip, deflate, sdch
Accept-Language: zh-CN,zh;q=0.8

Response:

HTTP/1.1 200 OK
Allow: OPTIONS, TRACE, GET, HEAD, POST
Server: Microsoft-IIS/7.5
Public: OPTIONS, TRACE, GET, HEAD, POST
X-Powered-By: ASP.NET
Date: Mon, 06 Jul 2015 02:43:12 GMT
Content-Length: 0

It ends here and doesn't request server to get data.

Do I miss something with web api cors preflight option request?