Hmm. It seems like putting a formula in the inline roll causes it to always be a 1. That's bizarre. If you put the number, it would work. Even putting the number inside an inline roll works. The introduction of a formula breaks it. Unrelated, with 4 items summed up, you'd want to divide by 4 to get the average, not 2. This is probably a bug that should be posted in the bugs forum.