How To Get Unmatched Rows In The Query

The following stored procedure is returning the correct row(s). But I am not sure it is correct.
In the stored procedure I need the variable passed in (@lotnum) in the dbo.tblBag_data compare with dbo.tblBag_results and return unmatch rows from dbo.tblBag_data. Basically I need the unmatched records in dbo.tblBag_data between two tables. For example there are five records. In dbo.tblBag_data 1st record contains lotnum(1000), bag1. next record contains lotnum(1000), bag2. .. last record contains lotnum(1000), bag5. In dbo.tblBag_results there are two bags. I need the three records that do not match up. Thanks!


CREATE PROCEDURE sp1
AS

declare @lotnum int

set @lotnum = 4056;
SELECT dbo.tblBag_data.work_ord_num, dbo.tblBag_data.work_ord_line_num, dbo.tblBag_data.bag_num, dbo.tblBag_data.lotnum, dbo.tblBag_data.bag_status
FROM dbo.tblBag_data
WHERE dbo.tblBag_data.lotnum = @lotnum AND dbo.tblBag_data.bag_num not in (select dbo.tblBag_results.bag_num from dbo.tblBag_results Where dbo.tblBag_results.lotnum = @lotnum)
GO