I am a new FileMaker Pro 15 user. I have started creating a simple accounting databases with a few tables. One table is for expenditures (I also have billing, salaries, other fund sources, etc.) and I have created a summary field in my Expenditures table that calculates the sum of entries in my “Amount” field. In the Relationships tab in the “Manage Database” menu I am trying to link that summary field to another table to do more calculations (a budget balance), but it is greyed out. Is there some other way to link summary fields from different table to create a final value, like a Final Budget Balance?