EF4.1中 DBContext.Entry就报错。无法修改数据

[徐家大哥]

DBContext.Entry就报错。无法修改数据
代码如下：
using (HSContext context= new HSContext())
{

context.DBSet<T>().Attach(entity);

var d = content.Entry(entity); //context.DBSet<T>().Entry(entity);
if(d.State== EntityState.Detached)
d.State = EntityState.Modified;

content.Entry(entity).State = EntityState.Modified;


content.SaveChanges();

}