DisplayAttribute没作用,why?

namespace WebBulletinBoard.DataAccess
{
    using System;
    using System.ComponentModel.DataAnnotations;
    using System.ComponentModel.DataAnnotations.Schema;

    [Table("BulletinBoardFile")]
    public partial class BulletinBoardFile
    {
        [Key] 
        public Guid FileKeyID { get; set; }
        [Display(Name = "展示日期", Order = 0)]
        [StringLength(10)]
        public string WorkDate { get; set; }
        [Display(Name = "公告抬头", Order = 1)]
        [StringLength(1024)]
        public string BulletinTitle { get; set; }
        [Display(Name = "公告描述", Order = 2)]
        [StringLength(1024)]
        public string BulletinContexnt { get; set; }
        [Display(Name = "发布人", Order = 4)]
        [StringLength(30)]
        public string UploadUser { get; set; }
        [Display(Name = "发布时间", Order = 3)]
        public DateTime? UploadDateTime { get; set; }
        [Display(Name = "文件名", Order = 5)]
        [StringLength(255)]
        public string FileName { get; set; }

        [Column(TypeName = "image")]
        public byte[] BinaryData { get; set; }
        [Display(Name = "显示天数", Order = 6)]
        public int DisplayDays { get; set; }

        public int? OderIndex { get; set; }

        [Column(TypeName = "timestamp")]
        [DatabaseGenerated(DatabaseGeneratedOption.Computed)]
        [MaxLength(8)]
        public byte[] RowVersion { get; set; }
    }
}

if (GridView1.Columns.Count > 0)
                {
                    var props = typeof(BulletinBoardFile).GetProperties();
                    foreach (var p in props)
                    {
                        var colParaObj = (DisplayAttribute)p.GetCustomAttributes(typeof(DisplayAttribute), false).FirstOrDefault();
                        if (colParaObj != null)
                        {
                            for (int i = 0; i < GridView1.Columns.Count; i++)
                            {
                                if (GridView1.Columns[i].HeaderText.Equals(p.Name))
                                {
                                    GridView1.Columns[i].HeaderText = colParaObj.Name;
                                    break;
                                }
                            }
                        }
                    }
                }