sql update

I am trying to make an update. If the session was cancelled I need to update the filed before that session to 1 and session that are after that session 2.

If i cancelling the session in the middle of the day I get what I need . but if I do the earliest session it marking as 1 when it should be 2

 /* -------------------------------------------------------------------- */
                /*  Lastly, find any adjoining sessions. These will be sessions within  */
                /*  30 minutes of the original cancelled session, where the car is the  */
                /*  same, but the instructor is different.                              */
                /* -------------------------------------------------------------------- */
              DECLARE @id tinyInt 
                SET @id = 0   
              UPDATE  a
                SET     a.adjoining = 1,
                        @id = a.hubLock = @id + 1 
                FROM    @Results a
                JOIN   (SELECT carKey, min(sessionStart) AS minStart, max(sessionEnd) AS maxEnd
                        FROM @Results
                        WHERE  1 IN (cancelled, contiguous)
                        GROUP BY carKey) c
                ON      c.carKey = a.carKey
                AND   ( a.sessionStart BETWEEN DATEADD(n, -29, maxEnd)   AND DATEADD(n, 29, maxEnd)
                    OR  a.sessionEnd   BETWEEN DATEADD(n, -29,minStart) AND DATEADD(n, 29, minStart) )

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