My DBA upgraded our server from 2005 to 2008 and when it did my SSIS packages stopped logging messages.
Well the default logging mechanism in 2005 logs to the dbo.sysdtslog90 table. Well in 2008 they changed the table name to dbo.sysssislog. Not a big deal, but you will never find something if you look in the wrong place.
Well now that I am looking at the right table, I noticed that my events were NOT showing up. In particular I was looking for the OnPreExecute and OnPostExecute methods. Poof gone, after many searches I stumbled across the following posts: