RAISERROR does not cause SQL task to fail - why?

-- This is the stripped procedure with no CATCH block. The OUTPUT parms do nothing.
-- This sproc will cause an SQL task to fail.

ALTER PROCEDURE [dbo].[sp_ThrowException]
@ERROR_NUMBER INT OUTPUT,
@ERROR_MESSAGE NVARCHAR(4000) OUTPUT,
@ERROR_SEVERITY INT OUTPUT,
@ERROR_STATE INT OUTPUT,
@ERROR_PROCEDURE NVARCHAR(126) OUTPUT,
@ERROR_LINE INT OUTPUT,
@FormattedMessage NVARCHAR(4000) OUTPUT
AS

BEGIN

SET NOCOUNT ON

-- this forces a "divide by zero" exception
SELECT 1 / 0 AS 'TRY' FROM view_OilRigs_REPORT R

END

-- This is the desired procedure with the CATCH block. The error information is being returned
-- to the SQL task through the OUTPUT parms.
-- This sproc will allow an SQL task to succeed.

ALTER PROCEDURE [dbo].[sp_ThrowException]
@ERROR_NUMBER INT OUTPUT,
@ERROR_MESSAGE NVARCHAR(4000) OUTPUT,
@ERROR_SEVERITY INT OUTPUT,
@ERROR_STATE INT OUTPUT,
@ERROR_PROCEDURE NVARCHAR(126) OUTPUT,
@ERROR_LINE INT OUTPUT,
@FormattedMessage NVARCHAR(4000) OUTPUT
AS

BEGIN TRY

-- SET NOCOUNT ON added to prevent extra result sets from
-- interfering with SELECT statements.
SET NOCOUNT ON

-- this forces a "divide by zero" exception
SELECT 1 / 0 AS 'TRY' FROM view_OilRigs_REPORT R

END TRY

BEGIN CATCH

SELECT
@ERROR_NUMBER = ERROR_NUMBER(),
@ERROR_MESSAGE = ERROR_MESSAGE(),
@ERROR_SEVERITY = ERROR_SEVERITY(),
@ERROR_STATE = ERROR_STATE(),
@ERROR_PROCEDURE = ERROR_PROCEDURE(),
@ERROR_LINE = ERROR_LINE(),
-- this renders the error message in command line format
@FormattedMessage = 'Msg ' + CAST(ERROR_NUMBER() AS NVARCHAR(20)) + ', ' +
'Level ' + CAST(ERROR_SEVERITY() AS NVARCHAR(20)) + ', ' +
'State ' + CAST(ERROR_STATE() AS NVARCHAR(20)) + ', ' +
'Procedure ' + ERROR_PROCEDURE() + ', ' +
'Line ' + CAST(ERROR_LINE() AS NVARCHAR(20)) + ', ' +
'Message: ' + ERROR_MESSAGE()

-- Use RAISERROR inside the CATCH block to return error
-- information about the original error that caused
-- execution to jump to the CATCH block.
RAISERROR
(
@ERROR_MESSAGE, -- Message text
@ERROR_SEVERITY, -- Severity
@ERROR_STATE -- State
)

END CATCH

-- I use this to run the sproc within Management Studio.

SET NOCOUNT ON;

DECLARE @local_ERROR_NUMBER INT
DECLARE @local_ERROR_MESSAGE NVARCHAR(4000)
DECLARE @local_ERROR_SEVERITY INT
DECLARE @local_ERROR_STATE INT
DECLARE @local_ERROR_PROCEDURE NVARCHAR(126)
DECLARE @local_ERROR_LINE INT
DECLARE @local_FormattedMessage NVARCHAR(4000)

EXEC [dbo].[sp_ThrowException]
@ERROR_NUMBER = @local_ERROR_NUMBER OUTPUT,
@ERROR_MESSAGE = @local_ERROR_MESSAGE OUTPUT,
@ERROR_SEVERITY = @local_ERROR_SEVERITY OUTPUT,
@ERROR_STATE = @local_ERROR_STATE OUTPUT,
@ERROR_PROCEDURE = @local_ERROR_PROCEDURE OUTPUT,
@ERROR_LINE = @local_ERROR_LINE OUTPUT,
@FormattedMessage = @local_FormattedMessage OUTPUT

SELECT
@local_ERROR_NUMBER AS ERROR_NUMBER,
@local_ERROR_MESSAGE AS ERROR_MESSAGE,
@local_ERROR_SEVERITY AS ERROR_SEVERITY,
@local_ERROR_STATE AS ERROR_STATE,
@local_ERROR_PROCEDURE AS ERROR_PROCEDURE,
@local_ERROR_LINE AS ERROR_LINE,
@local_FormattedMessage AS FormattedMessage

BEGIN CATCH

PRINT 'some error message'

RAISERROR('some error message',16,1)

END CATCH