dear Grant Fritchey,
thank you 4 your prompt reply. i found the issue what i mention in my query. when my server was 2000 and i was creating jobs and define a category which ID was 4. but after upgrading to 2012, there is not any category ID of 4. that's way in JOB ACTIVITY MONITOR can't retrieve those jobs name which category ID was 4.
SELECT * from dbo.syscategories ORDER BY category_id ASC
GOin 2000, category_id = 4 exists but in 2008, category_id = 4 doesn't exist.
just i updated dbo.sysjobs table
-- SELECT * from dbo.sysjobs
SET category_id = 10
WHERE job_id = '<JOB_ID>'
AND category_id = 4
thanks and regards,