JQuery Json error: Object does not support this property or method

ERROR: Microsoft JScript Runtime Error: Object does not support this property or method

this is how json2 is calling from:

   **var json = JSON2.stringify(settings.data);**

      

        
        
        
      

    

I am using WCF service to pull data and it is very easy to test and it returns data to me from wcf service but it doesnt work on json2.js at line number 314-316

// We split the first stage into 4 regexp operations in order to work around
// crippling inefficiencies in IE and Safari regexp engines. First we
// replace all backslash pairs with '@' (a non-JSON character). Second, we
// replace all simple value tokens with ']' characters. Third, we delete all
// open brackets that follow a colon or comma or that begin the text. Finally,
// we look to see that the remaining characters are only whitespace or ']' or
// ',' or ':' or '{' or '}'. If that is so, then the text is safe for eval.

                if (/^[\],:{}\s]*$/.test(text.replace(/\\["\\\/bfnrtu]/g, '@').
replace(/"[^"\\\n\r]*"|true|false|null|-?\d+(?:\.\d*)?(?:[eE][+\-]?\d+)?/g, ']').
replace(/(?:^|:|,)(?:\s*\[)+/g, ''))) {

      

        
        
        
      

    

that's what I'm doing

    // *** Generic Service Proxy class that can be used to 
// *** call JSON Services generically using jQuery
// *** Depends on JSON2 modified for MS Ajax usage
function serviceProxy(wjOrderServiceURL) {
    var _I = this;
    this.ServiceURL = wjOrderServiceURL;

    // *** Call a wrapped object
    this.invoke = function (options) {

        // Default settings
        var settings = {
            serviceMethod: '',
            data: null,
            callback: null,
            error: null,
            type: "POST",
            processData: false,
            contentType: "application/json", 
            dataType: "text",
            bare: false
        };

        if (options) {
            $.extend(settings, options);
        }

        // *** Convert input data into JSON - REQUIRES Json2.js
        var json = JSON2.stringify(settings.data);

        // *** The service endpoint URL
        var url = _I.ServiceURL + settings.serviceMethod;
      debugger
        $.ajax({
            url: url,
            data: json,
            type: settings.type,
            processData: settings.processData,
            contentType: settings.contentType,
            timeout: settings.timeout,
            error: settings.error,
            dataType: settings.dataType,
            success:
                    function (res) {
                        if (!settings.callback) { return; }

                        // *** Use json library so we can fix up MS AJAX dates
                        var result = JSON2.parse(res);
                        debugger
                        if (result.ExceptionDetail) {
                            OnPageError(result.Message);
                            return;
                        }

                        // *** Bare message IS result
                        if (settings.bare)
                        { settings.callback(result); return; }

                        //http://encosia.com/2009/07/21/simplify-calling-asp-net-ajax-services-from-jquery/
                        if (result.hasOwnProperty('d'))
                        { return settings.callback(result.d); }
                        else
                        { return result; }


                        // *** Wrapped message contains top level object node
                        // *** strip it off
                        //                        for (var property in result) {
                        //                            settings.callback(result[property]);
                        //                            break;
                        //                        }
                    }
        });
    };
}



 function GetFederalHolidays() {

        $("#dContacts1").empty().html('Searching for Active Contacts...');  
        ContactServiceProxy.invoke({ serviceMethod: "Holidays",
            callback: function (response) {
    //           ProcessActiveContacts1(response);
                debugger
            },
            error: function (xhr, errorMsg, thrown) {
                postErrorAndUnBlockUI(xhr, errorMsg, thrown);
            }
        });        
}

      

        
        
        
      

    

wcf returns me a simple string

  public List<string> Holidays()
        {
            List<string> s = new List<string>();
            s.Add("01/01/2010");
            s.Add("02/01/2010");
            s.Add("03/01/2010");
            s.Add("04/01/2010");
            s.Add("05/01/2010");
            return s;

        }

      

        
        
        
      

    

any help what i am doing wrong? i am trying to go from dataType: text to json but i am getting the same error above.