If you have any experience with SSIS, you have come to realize that the error codes for SSIS are not the same as the error codes for SQL Server. Personally, I would have preferred the same error code for the same error. For example, a violation of a unique constraint in SSIS is -1071607685 while the same violation in T-SQL is 2627.
SSIS error codes are typically hard to track down, but you can find them at http://msdn.microsoft.com/en-us/library/ms345164.aspx.
Is my curmudgeonly nature showing?