请那位.NET编程高手帮我看以下程序，在生成时报错：int.TryParse(string, out int)最匹配的重载方法具有一些无效参。正确的写法应该是什么？我是新手，在读他人写的程序，对您的帮助非常感谢！！

 public static int GeIntParam(HttpRequest request, string name, int defaultValue)
        {
            int num = defaultValue;
            if (request != null)
            {
                string str = defaultValue.ToString();
                if (request.QueryString[name] != null)
                {
                    str = request.QueryString[name].ToString();
                }
                else if (request.Form[name] != null)
                {
                    str = request.Form[name].ToString();
                }
                if (!int.TryParse(str, num))
                {
                    num = defaultValue;
                }
            }
            return num;
        }