EXECUTE WITH RESULT SETS failing in SQL Server 2012

[TheBugSlayer]

All,

I have a Data Flow task in an SSIS package wich contains an OLE DB Source component. The component's data access mode is SQL Command. The command is

exec AccessionCountsByReceivedDate ?, ?

. However, the package complains about being unable to retrieve column information from the data source. So I changed the statement to

exec AccessionCountsByReceivedDate '2013-09-19', '2013-09-19' 
WITH RESULT SETS 
(
	(groupname as varchar(1000),
	[description] as varchar(1000),
	accessioncount as int,
	avgtat as double)
);

and in SSMS and SSDT the error is

Incorrect syntax near 'RESULT'

. This being a new statement in 2012, my lack of familiarity with it is obviously a problem. Can someone tell me what is wrong with the statement?

I have similar SSIS packages with connections to SQL Server servers and they work just fine. This issue is caused by the use of a temporary table in the stored procedure. The programmer who wrote the SP is only available twice a week and I needed to complete the SSIS package today.

Thanks for your help.

MCP SQL Server 2000, MCTS SQL Server 2005, MCTS SQL Server 2008 (DBD, DBA)