I'm sorry, I might be misunderstanding or something, but in the description of what you need, you say that you need to sum if the activity stage is accepted OR closed won. In calculation 1, where you get no results, you have calculated if the activity stage is accepted AND closed won. Could that be the reason you do not get any results?
Change the AND to an OR and I think you will get results. From your table example it can never be both.
For the second calculation, there will be the same issue at least, but also if you use just record count instead of sum recordcount and put it in a table, it will automatically sum, so you don't need to aggregate.
Hope that helps,