SQL Server 2012 :: Stored Procedure Not Running To Completion And Not Returning Results Set

I have stored procedure

ALTER PROCEDURE dbo.usp_Create_Fact_Job (@startDate date, @endDate date) AS
/*--Debug--*/
--DECLARE @startDate date
--DECLARE @endDate date

--SET @startDate = '01 APR 2014'
--SET @endDate = '02 APR 2014'
;
/*-- end of Debug*/
WITH CTE_one AS ( blah blah blah)

SELECT a whole bunch of fields from the joined tables and CTEs...When I run the code inside the stored procedure by Declaring and setting the start and enddates manually the code runs in 4 minutes (missing some indexes ).When I call the stored procedure with the ExEC

DECLARE@return_value int
EXEC@return_value = [ClaimCenter].[usp_Create_Fact_Job]
@startDate = '01 apr 2014',
@endDate = '01 apr 2014'
SELECT'Return Value' = @return_value

It never returns a results set but doesn't error out either. I have left it for 40 minutes and still no joy.The sproc is reasonably complicated; 6 CTEs to find the most recent version of records and some 2 joins to parent tables (parent and grandparent), 3 joins to child tables (child, grandchild and great grandchild) and 3 joins to lookup views each of which self references a table to filter for last version of a record.