Using a BitMask in a Where Clause

BEGIN 
DECLARE @MailDelivery int, 
        @EmailDelivery int, 
        @FaxDelivery int, 
        @ParamVal int, 
        @ZeroVal int
 
SET @MailDelivery  = 1 --(0001)
SET @EmailDelivery = 2 --(0010)
SET @FaxDelivery   = 4 --(0100)
 
SET @ParamVal = 1
SET @ZeroVal =  0
 
IF @ParamVal = 0
SET @ZeroVal = NULL
 
SET @ParamVal = isnull(@ParamVal, 0)
 
SELECT Id, 
       --BusinessEventDate, 
       DeliveryFlags, 
       (isnull(DeliveryFlags,0) & @ParamVal) AS BitMask 
FROM   Mailsets
WHERE (BusinessEventDate > '8/28/2007')
--Check the appropriate bit.  
  AND (
        (isnull(DeliveryFlags,0) & @ParamVal) = @ParamVal + isnull(@ZeroVal, isnull(DeliveryFlags,0))
      )
 
END 
GO