jquery/ajax- post an array (not empty) to a c# webservice's function
===

I try to pass an array contains two integers to a webservice's function:

    [WebMethod]
    [ScriptMethod(UseHttpGet = true, ResponseFormat = ResponseFormat.Json)]
    public bool sample(int number, int[] numbers)
    {
        return (numbers.Sum() > number);
    }

I do it with jquery.ajax:

    var arr = ['20', '89'];

    $.ajax({ url: "Registration.asmx/sample",
        data: jQuery.param({ 'number': '300', 'numbers[]': arr }),
        type: "POST",
        success: function (data) {
            $('#result').html(data.toString());
        },
        error: function (xhr, ajaxOptions, thrownError) {
            $('#result').html(jQuery.param({ 'number': '300', 'numbers': arr }) + "<br/><br/>" +
                          thrownError + "<br/><br/>" +
                          xhr.responseText);
        }
    });

but I always get a server internal error about an empty array(I think)![none][1]


  [1]: http://i.stack.imgur.com/flpMG.jpg