无法向Sql Server 2005表添加权限

USE [Messenger];
GO
GRANT DELETE ON [dbo].[Messages] TO [MM_TableAccess];
GO
GRANT INSERT ON [dbo].[Messages] TO [MM_TableAccess];
GO
GRANT SELECT ON [dbo].[Messages] TO [MM_TableAccess];
GO
GRANT UPDATE ON [dbo].[Messages] TO [MM_TableAccess];
GO

USE [Messenger];
GO
SET ANSI_NULLS ON;
GO
SET QUOTED_IDENTIFIER ON;
GO
CREATE TABLE [dbo].[Messages] (
[MessageID] bigint IDENTITY(1, 1) NOT NULL,
[ParentID] bigint NOT NULL,
[CategoryID] bigint NOT NULL,
[PostedByID] bigint NOT NULL,
[DatePosted] datetime NOT NULL,
[MessageTitle] nvarchar(50) NULL,
[MessageBody] nvarchar(4000) NOT NULL,
CONSTRAINT [PK__Messages__07F6335A]
PRIMARY KEY NONCLUSTERED ([MessageID] ASC)
WITH ( PAD_INDEX = OFF,
FILLFACTOR = 100,
IGNORE_DUP_KEY = OFF,
STATISTICS_NORECOMPUTE = OFF,
ALLOW_ROW_LOCKS = ON,
ALLOW_PAGE_LOCKS = ON )
ON [PRIMARY],
CONSTRAINT [FK_ParentID]
FOREIGN KEY ([ParentID])
REFERENCES [dbo].[Messages] ( [MessageID] ),
CONSTRAINT [FK_CategoryID]
FOREIGN KEY ([CategoryID])
REFERENCES [dbo].[Categories] ( [CategoryID] )
ON DELETE CASCADE

)
ON [PRIMARY];
GO