sorry, i'm still not really sure what you're going for here... i can tell you that sum() is not doing anything in that specific formula.

will the colleague only work in one specific queue per day? and then row 2 looks like the target # for one hour in a specific queue? since you're saying adding different queues gives you the error i'm guessing the answer to the first question is no - they might work in multiple queues in a given day? how do we know how many hours they spent in a given queue?