Error 0xC0015005 when exec'ing SP from SSIS

rror trying to execute a stored procedure from SSIS Execute SQL Task:
"Exception from HRESULT: 0xC0015005".

So far, googling, SQLTeam, SQLServerCentral, SQL-Server-Performance and BOL searches have turned up .... 0.

What I have is the following SP:
----sp code---
Use
DataStore


-- Drop stored procedure if it already exists
IF EXISTS (
SELECT *
FROM INFORMATION_SCHEMA.ROUTINES
WHERE SPECIFIC_SCHEMA = N'dbo'
AND SPECIFIC_NAME = N'usp_EXAMPLE_ProductAvailability_perTPNB'
)
DROP PROCEDURE dbo.usp_EXAMPLE_ProductAvailability_perTPNB
GO

CREATE PROCEDURE dbo.usp_EXAMPLE_ProductAvailability_perTPNB
@TPNB int, @TPNBAvailable varchar(11) OUTPUT
AS

--Created By: Regan
--Created On: 2006-05-25

--Version: 0.1 - initial creation

--SQL Version: 2005 SP0. This should be compatiable back to at least 7.0 since it is only a table create,
-- but since it is for an SSIS package, that is not advisable

--Overview:
--This script is a very basic 1st stab at a SP retrieving a value, based on a TPNB found.

--ToDo:
-- flesh this out into a properly thought-out, detailed SP.

--Sample Usage:
-- DECLARE
-- @TPNB int,
-- @Available varchar(11),
-- @RetrunCode int
--
-- EXEC @ReturnCode = usp_EXAMPLE_ProductAvailability_perTPNB @TPNB=@TPNB, @TPNBAvailable=@Available OUTPUT
-- IF @ReturnCode <> 0
-- PRINT 'An Error occurred : @ReturnCode = ['+str(@ReturnCode)+']'
-- ELSE
-- PRINT 'SUCCESS : @Available = ['+(@Available)+']'

DECLARE
@ErrorDescription NVARCHAR(250),
@Error INT,
@RowCount INT

--Check Pre-Contract - we must receive a TPNB number
IF (@TPNB = 0) or (@TPNB is null)
BEGIN
SET @ErrorDescription = '### ERROR - Pre-CONTRACT FAILURE : Stored Procedure [usp_EXAMPLE_ProductAvailability_perTPNB] received an invalid input parametre ['+isnull(cast(@TPNB as varchar(16)),'NULL')+'] and is FAILING - ERROR ###'
SET @Error = 1 --Custom value for Contract Failure
RAISERROR (@ErrorDescription,10,1,@Error)
RETURN @Error
END

--Contract Held - get availability
SELECT @TPNBAvailable =
CASE
WHEN NetQuantityAvailable <= 0 THEN 'Unavailable'
WHEN NetQuantityAvailable > 0 THEN 'Available'
END
FROM dbo.EXAMPLE_vwTPNBQuantity
WHERE TPNB = @TPNB

--ErrorChecking
SELECT @Error = @@Error, @RowCount = @@RowCount
IF @Error <> 0
BEGIN
SET @ErrorDescription = '### ERROR - SQL FAILURE : Stored Procedure [usp_EXAMPLE_ProductAvailability_perTPNB] failed with @@Error of ['+cast(@Error as varchar(16))+'] and is FAILING - ERROR ###'
RAISERROR (@ErrorDescription,10,1,@Error)
RETURN @Error
END ELSE
IF @RowCount <> 1
BEGIN
SET @ErrorDescription = '### ERROR - TPNB VALUE FAILURE : Stored Procedure [usp_EXAMPLE_ProductAvailability_perTPNB] Returned : ['+cast(@RowCount as varchar(16))+'] rows using input TPNB of ['+cast(@TPNB as varchar(16))+'] and is FAILING - ERROR ###'
SET @Error = 3 --Custom value for TPNB Failure
RAISERROR (@ErrorDescription,10,1,@Error)
RETURN @Error
END

--Post contract check of @TPNBAvailable value necessary?
RETURN @Error
GO

----/code--

my Execute SQL task command is:
EXEC ?= dbo.usp_EXAMPLE_ProductAvailability_perTPNB ?, ? OUTPUT

the full error message is:
[Execute SQL Task] Error: An error occurred while assigning a value to variable "varTPNBAvailable": "Exception from HRESULT: 0xC0015005".

Any thoughts

Panic, Chaos, Disorder ... my work here is done --unknown

Thanks Satya - just found that as well:

I found my problem - I had specified that the SP returns RESULTSET of SINGLE ROW - whereas I needed to say that RESULTSET was NONE.

The following page gave me the answer, and should be bookmarked (imho) for all intrepid SSIS developers:
http://msdn2.microsoft.com/en-us/library/ms345164.aspx

Cheers

Panic, Chaos, Disorder ... my work here is done --unknown