Help On Partitioning Column Was Not Found.

Hi,

I don't know if I missed anything. I have 2 member tables and one
partition view in SQL 2000 defined as following

CREATE VIEW Server1.dbo.UTable
AS
SELECT*
FROMServer1..pTable1
UNION ALL
SELECT*
FROMServer2..pTable2

CREATE TABLE pTable1 (
[ID1] [int] IDENTITY (1000, 2) NOT NULL ,
[ID2] [int] NOT NULL ,

...<other columns>.........

CONSTRAINT [PK_tblLot] PRIMARY KEY CLUSTERED
(
[ID1],
[ID2]
) ON [PRIMARY] ,
CHECK ([ID2] = 1015)
) ON [PRIMARY]


CREATE TABLE [pTable2] (
[ID1] [int] IDENTITY (1001, 2) NOT NULL ,
[ID2] [int] NOT NULL ,

...<other columns>.........

CONSTRAINT [PK_tblLot] PRIMARY KEY NONCLUSTERED
(
[ID1],
[ID2]
) WITH FILLFACTOR = 90 ON [PRIMARY] ,
CHECK ([ID2] <1015)
) ON [PRIMARY]


SELECT is working fine. However, I got error message if I issue an
update command such as

UPDATE UTable
SET somecol = someval
Where somecol2 = somecond

Server: Msg 4436, Level 16, State 12, Line 1
UNION ALL view 'UTable' is not updatable because a partitioning column
was not found.

Anyone have any idea? ID2 is my partition column, why the SQL 2K
doesn't see it. It is a part of primary key, having checking
constrain, and no other constrain on it. Am I missing something?

Thanks a lot.