For Each Loop / Expression Behavior

Hello all,



I have a question concerning properties, variables, expressions, and their interactions within a for each loop. I'm still hammering out some details with the SSIS package I have been posting about recently, and I came across this bit of what may or may not be odd behavior (and it may only be odd because it's not doing what I expect).



I have a number of execute sql and script tasks inside a for each container. I am using one of the script tasks to flip a couple of variables on and off that I thought I could use to disable or enable later tasks during run time. What seems to be happening is that when I set disable on those tasks to true, I can no longer run them again in later iterations of the loop.



In other words: I can loop through it three times, with disable set to false via an expression - then the fourth iteration evaluates to true and disables the appropriate tasks, and then any later iterations no longer run any of the disabled tasks whether the expression evaluates true or false. Once disabled, they stay disabled, regardless of expression.



Is this a bug, or is there a "proper" way to do this? Am I foolish to assume that a "dynamic" run-time property is actually changeable with each iteration of a loop?