MVC4 method Unable to recieve array using XMLHttpRequest

i am sending list of GUID from view to controller by XMLHttpRequest but method is not recieving my that array

here is my jQuery function

function SendMsg() {
            $('#progressbar').show();
            $('#progressbar').html(imageDiv);
            //alert(selectedUserId);
            $('.load').html('<p class="fg-white">loading...</p>');
            var formdata = new FormData();
            var fileInput = document.getElementById('files');
            var messageText = $("#messageText").val();
            if (messageText != "") {
                for (i = 0; i < fileInput.files.length; i++) {
                    formdata.append(fileInput.files[i].name, fileInput.files[i]);
                }
                var xhr = new XMLHttpRequest();
                xhr.addEventListener("load", uploadComplete, false);
                xhr.addEventListener("error", uploadFailed, false);
                xhr.addEventListener("abort", uploadCanceled, false);
                // + '&recieverUserInfoId=' + JSON.stringify(recieverUserInfoId) + '&isBulkMsg='+isBulkMsg);
                xhr.open('POST', '/Message/AddMessageFile?messageText=' + messageText + '&recieverUserInfoId=' + selectedUserId);// + '&isBulkMsg='+isBulkMsg);
                alert("/Message/AddMessageFile?messageText=" + messageText + "&recieverUserInfoId=" + JSON.stringify(recieverUserInfoId));
                xhr.upload.addEventListener("progress", uploadProgress, false);
                xhr.send(formdata);
            }
            setTimeout(function () {
                $('.cleartext').val("");
                $('#files').val("");
            }, 1500);
        }

here the method named AddMessageFile in MessageController

    public void SendMessage(string messageText, Guid[] recieverUserInfoId, string url, bool isBulkMsg)
        {


            List<Guid> totalUserIdList = new List<Guid>();
            totalUserIdList = recieverUserInfoId.ToList(); 

}

"Error: An exception of type 'System.ArgumentNullException' occurred in System.Core.dll but was not handled in user code"