Whatz Wrong With This Stored Proc

Hi,


I'm getting an error ERROR 137: Must declare the variable '@' when I click the check sysntax button on my store proc window. Any ideas on how to resolve this??








CREATE PROCEDURE CabsSchedule_GetPrevYearMonth


AS


DECLARE @prvYearMonth int


DECLARE @prvYear int


DECLARE @prvMonth int





BEGIN


SET @prvYearMonth = (SELECT MAX(YearMonth) FROM CabsSchedule)


IF ((SELECT COUNT(*) FROM CabsSchedule WHERE YearMonth = @ prvYearMonth) > 15)


ELSE


BEGIN


IF (SUBSTRING(CAST(@prvYearMonth AS VarChar(6)), 5, 2) = '01')


BEGIN


SET @prvMonth = 12


SET @prvYear = CAST(SUBSTRING(CAST(@prvYearMonth AS VARCHAR(6)),1,4) AS INT) - 1


SET @prvYearMonth = CAST(CAST(@prvYear AS VARCHAR(4)) + CAST(@prvMonth AS VARCHAR(2)) AS INT)


END


END


END


GO











Thanks,