ASP.Net MVC 3 - JSON Model binding to array

I am on ASP.Net MVC 3, and going by the feature list supported in at, i should be able to get default json model binding working out of the box. However i havent been successful in binding an array/collection from json to the action method parameter. Although I did get simple json object binding working right. Would greatly appreciate if an expert here could tell me what i am doing wrong.

Here is the code:

Server side code first:

//Action Method

 public JsonResult SaveDiscount(IList<Discount> discounts)
    {
       foreach(var discount in discounts)
       {
       ....
       }
    }

//View model

public class Discount
{
    string Sku{get; set;}
    string DiscountValue{get; set;}
    string DiscountType{get; set;}

}

//client side(jquery/js):

    var discount = {};
    var jsondatacoll = [];
    $('#discountgrid tr').each(function () {

        sku = $(this).find("td").eq(1).html();
        discValue = $(this).find('.discval').val();
        discType = $(this).find('.disctype').val();

        discount = { Sku: sku, DiscountType: discType, DiscountValue: discValue};
        jsondatacoll.push(discount);
        }
    })
    if (jsondatacoll.length > 0) {
        var catalogDiscount = JSON.stringify(jsondatacoll);

        $.ajax(
        {
            url: '/url/savediscount',
            type: 'POST',
            data: catalogDiscount,
            dataType: 'json',
            contentType: 'application/json; charset=utf-8',
            success: function (data, textStatus, jqXHR) {
                ...                   
            },
            error: function (objAJAXRequest, strError) {                 
               ...
            }
        }
     );   //ajax
    }

i did check the json payload in fiddler and it look like below:

[
    {"Sku":"sku1","DiscountType":"type1","DiscountValue":"10"},     
    {"Sku":sku2","DiscountType":"type1","DiscountValue":"12"}, 
    {"Sku":"sku3","DiscountType":"type2","DiscountValue":"40"}
]

And on the server side i do see the IList<Discount> discounts has been populated with 3 empty Discount objects - meaning the properties are null but the length of the discounts argument is 3.