ProductDBEntities db = new ProductPDBEntities();

    var pro = from u in db.Products where u.PID == 1 select u;

    if (pro != null)
    {
        GridView1.DataSource = pro;
        GridView1.DataBind();
    }

并得到这个错误.

System.InvalidOperationException:
Sequence contains more than one
element

有人可以告诉我,我做错了什么？