WCF - (504) The server did not return a response for this request

I have a JSONP WCF Endpoint and am trying to track down why I am getting a 504 error. HTTP/1.1 504 Fiddler - Receive Failure Content-Type: text/html Connection: close Timestamp: 11:45:45:9580 ReadResponse() failed: The server did not return a response for this request. I can set a breakpoint anywhere inside of my Endpoint, step through code, see it successfully gather the data required for the response, hit the final line of code, then as soon as I step out of the WCF call I get a 504 error. This was working last week! ``` [AspNetCompatibilityRequirements(RequirementsMode = AspNetCompatibilityRequirementsMode.Allowed)] [ServiceContract(Name = "NegotiateService", Namespace = "http://rivworks.com/Services/2009/01/15")] public class NegotiateService //: svcContracts.INegotiateService { public NegotiateService() { } [OperationContract] [WebGet(ResponseFormat = WebMessageFormat.Json)] public dataObjects.NegotiateSetup GetSetup(string method, string jsonInput) { dataObjects.NegotiateSetup resultSet = new dataObjects.NegotiateSetup(); using (RivFeedsEntities1 _dbFeed = new FeedStoreReadOnly(AppSettings.FeedAutosEntities_connString, "", "").ReadOnlyEntities()) { using (RivEntities _dbRiv = new RivWorksStore(AppSettings.RivWorkEntities_connString, "", "").NegotiationEntities()) { // Deserialize the input and get all the data we need... Newtonsoft.Json.Linq.JObject o = Newtonsoft.Json.Linq.JObject.Parse(jsonInput); string urlRef = String.Format("{0}", o["ref"]).Replace("\"", ""); string clientDate = String.Format("{0}", o["dt"]).Replace("\"", ""); string ProductID = String.Format("({0})", o["productId"]).Replace("\"", ""); string SKU = String.Format("{0}", o["sku"]).Replace("\"", ""); string env = String.Format("{0}", o["env"]).Replace("\"", ""); IList<Product> efProductList = null; Product workingProduct = null; vwCompanyDetails workingCompany = null; bool foundItem = false; if (!String.IsNullOrEmpty(SKU)) efProductList = _dbRiv.Product.Include("Company").Where(a => a.SKU == SKU).ToList(); else if (!String.IsNullOrEmpty(ProductID)) efProductList = _dbRiv.Product.Include("Company").Where(a => a.ProductId == new Guid(ProductID)).ToList(); foreach (Product product in efProductList) { if (String.IsNullOrEmpty(product.URLDomain)) { var efCompany = _dbRiv.vwCompanyDetails .Where(a => a.defaultURLDomain != null && a.CompanyId == product.Company.CompanyId) .FirstOrDefault(); if (efCompany != null && urlRef.Contains(efCompany.defaultURLDomain)) { foundItem = true; workingProduct = product; workingCompany = efCompany; } } else { if (urlRef.Contains(product.URLDomain)) { foundItem = true; workingProduct = product; workingCompany = _dbRiv.vwCompanyDetails .Where(a => a.CompanyId == product.Company.CompanyId) .FirstOrDefault(); } } } if (foundItem) { try { // Update the resultSet... if (workingProduct != null && workingCompany != null) { string rootUrl = String.Empty; try { rootUrl = AppSettings.RootUrl; } catch { rootUrl = env + @"/"; } resultSet.button = workingProduct.ButtonConfig; resultSet.swfSource = String.Format(@"{0}flash/negotiationPlayer.swf", rootUrl); resultSet.gateway = rootUrl; resultSet.productID = workingProduct.ProductId.ToString(); resultSet.buttonPositionCSS = workingProduct.buttonPositionCSS; } } catch (Exception ex) { log.WriteLine(" ERROR: ", ex.Message); log.WriteLine("STACK TRACE: ", ex.StackTrace); } } } } return resultSet; } } ``` My web.config: ``` <!-- WCF configuration --> <system.serviceModel> <behaviors> <endpointBehaviors> <behavior name="JsonpServiceBehavior"> <webHttp /> </behavior> </endpointBehaviors> </behaviors> <services> <service name="RivWorks.Web.Service.NegotiateService"> <endpoint address="" binding="customBinding" bindingConfiguration="jsonpBinding" behaviorConfiguration="JsonpServiceBehavior" contract="RivWorks.Web.Service.NegotiateService" /> </service> </services> <extensions> <bindingElementExtensions> <add name="jsonpMessageEncoding" type="RivWorks.Web.Service.JSONPBindingExtension, RivWorks.Web.Service, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null" /> </bindingElementExtensions> </extensions> <bindings> <customBinding> <binding name="jsonpBinding" > <jsonpMessageEncoding /> <httpTransport manualAddressing="true"/> </binding> </customBinding> </bindings> </system.serviceModel> ``` As I said, the code runs all the way through so I am trying to figure out why it is not sending a response.