In preparing a demo for the chalk and talks I have been building an Integration sevices package. In the package I am using the Execute Process task to run SQLCMD. What I couldn't understand was this was completeing successfully but task later on that depended on the stuff done by sqlcmd failed. As though the SQLCMD process had failed.
On investigation I found that I had set FailTaskIdReturnCodeIsNotSuccessValue to false. This meant that although SQLCMD had failed the task ignored the failure and the package carried on. Oops
So lesson learned make sure you have your FailTaskIdReturnCodeIsNotSuccessValue set to true if you care about the result of your process.