Getting the LATEST DATE in the table

How to modify the below procedure in order to get the latest date ( the biggest value ) in the column "Deadline", type smalldatetime, ( example: 24/02/2007 00:00:00 ) for a given customer "UserName" ?

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CREATE PROCEDURE GetLatestDate

(@.UserName VARCHAR(50)

AS

SELECT Deadline

FROM CustomerItems

WHERE UserName = @.UserName

try

select max(Deadline)from CustomerItemswhere UserName = @.UserName

|||Thank you,jdingo .sql