Help for failed request log

I hava a ajax call wcf in asp.net mvc 4 web site. It post the data to the server. However I found the error" Endpoint not found" error. By checking log file. I got.

<failedRequest url="http://localhost:8080/wscccService.svc/"
           siteId="1"
           appPoolId="Clr4IntegratedAppPool"
           processId="8052"
           verb="GET"
           remoteUserName=""
           userName=""
           tokenUserName="hui-PC\hui"
           authenticationType="anonymous"
           activityId="{00000000-0000-0000-3E00-0080000000FD}"
           failureReason="STATUS_CODE"
           statusCode="200"
           triggerStatusCode="404"
           timeTaken="499"
           xmlns:freb="http://schemas.microsoft.com/win/2006/06/iis/freb"><Event xmlns="http://schemas.microsoft.com/win/2004/08/events/event"><System><Provider Name="WWW Server" Guid="{3A2A4E84-4C21-4981-AE10-3FDA0D9B0F83}"/><EventID>0</EventID><Version>1</Version><Level>5</Level><Opcode>2</Opcode><Keywords>0x100</Keywords><TimeCreated SystemTime="2013-07-16T23:27:11.577Z"/><Correlation ActivityID="{00000000-0000-0000-3E00-0080000000FD}"/><Execution ProcessID="8052" ThreadID="7120"/><Computer>HUI-PC</Computer></System>
             // many blah blah

I don't understand it at all. The client side code:

<script lang="javascript" type="text/javascript">
        function ttsFunction() {
            serviceUrl = "http://localhost:8080/wscccService.svc/RunTts";
            var data = new Object();
            data.text = $('#speak').val();
            var jsonString = JSON.stringify(data);$.ajax({
                type: 'POST',
                url: serviceUrl,
                data: jsonString,
                contentType: 'application/json; charset=utf-8',
                dataType: 'json',
                error: function (xhr,status,error) {
                    console.log("Status: " + status);
                    console.log("Error: " + error);
                    console.log("xhr: " + xhr.readyState);
                },
                statusCode: {
                    404: function() {
                        console.log('page not found');
                    }
                }
            });
        }</script>

The service code:

namespace service
{
    [AspNetCompatibilityRequirements(RequirementsMode = AspNetCompatibilityRequirementsMode.Allowed)]
    [ServiceBehavior(IncludeExceptionDetailInFaults = true)]
    public class wservice:Iwservice
    {
        public string RunTts(string value)
        {
            using (SpeechSynthesizer synth = new SpeechSynthesizer())
            {
                // Configure the audio output. 
                synth.SetOutputToDefaultAudioDevice();
                synth.Speak(value);
                return "";
            }
        }
    }
}

Thanks.