It would look something like this:
SUM([datasource1].[measure1]) + SUM([datasource2].[measure2])
Technically you're not using measures from one sheet and another sheet. You are using measures from one source and another source.
Or ... maybe I'm not getting the question you are asking.
when I write:
sum([Summary].[ADR]) /worksheet name and measure
I get an Error: "undefined field..."
OK. Your response clarifies my misunderstanding of your question.
My response was about accessing measures from other DATA SOURCES.
You can’t reference another sheet.
What you’ll have to do is create the same data collection and conditions in your current sheet to access what you see in another sheet.
Post a sample workbook and we can work together on making that happen (if possible. Sometimes it’s simply not possible – especially when the conditions (filter values, etc.) conflict. But there are often things you can do to make it work.)