Thanks so much for having a look. That's a big help.
Is there any chance you could explain why it is that a blend through Order ID was affected by the filter while one through Order Date was not?
Order ID is smaller grain of Department in this case, that's the reason, when you filter "Department" Order ID is also filtered.
So you need to use bigger grain than "Department" to show stable reference number nevertheless of "Department" filter..
In this case, there are no appropriate filed to meet that criteria. So you should have no link.
At the same time, your graph has "Date" as X-Axis, then you can link with "date" to show "Daily Total of all Department".
Perfectly clear now. Thanks very much!
You are very welcome.