Inserting A Unique Value In A Column

hi,
In the below code, i am trying to insert the identity value into the 2nd column of the Symp_Quote table. Schema of the table Symp_Quote is as follows.

CRAETE TABLE Symp_Quote
(
QuoteRevision_ID INT PK,
DocumentSeq TINYINT PK,
DocumentDisplayName VARCHAR (255)
)

1st column data is coming from the select statement. but for 2nd column i have to insert identity or some unique value. to do that i was trying withe the following code, but it failed.

INSERT INTO Symp_Quote
(
QuoteRevision_ID,
DocumentSeq,
DocumentDisplayName
)
SELECT
S.QuoteRevision_ID,
IDENTITY (INT,1,1) AS DocumentSeq,
T.Name,
FROM Symp S
INNER JOIN Trilogy T
ON
SQR.tril_gid = FQR.tril_gid



kindly correct me whr I am wrong.........


Thanks,
Rahul Jha