Concatenating Notes Field in Powerpivot

Hello I have a financial budget rollup model in powerpivot. My facts table with all the projected budgets per account and per business unit has notes from the people who put the budget together. The rollup displays information for all the business units together but can be filtered down to individual business units too. I want to concatenate the notes on the GL code as a measure but can't figure out how to make it work. So depending on the filtering of the table it would match the financial information presented. Any help with this concatenate measure? I tried concatenate x with a variety of calculate and such but couldn't get it to work.