Sounds like both expressions are evaluating as true all the time. Make sure that %nextExchange specifies Date as the result type.
Your Date function calls seem to have omitted the year, but I am guessing that this is a typo as that should trigger an error message if you actually tried to set it up that way.
PS, you can simplify your calcs by leaving out the date function call all together:
People::%nextExchange < Get ( CurrentDate ) + 30
Dates in FileMaker are really number fields that record the number of days from 12/31/0000 to the date shown/entered in the field and thus you can compute dates by adding and subtracting the number of days needed to compute the desired date.
A huge thank you!!! Sometimes it is the most simple of solutions and I need just a few more brain cells than I have at the ready to get it done. As usual you swoop in immediately and provide the answer. It was the %nextExchange that was set to a number and not a date. Walah!
p.s. Thank you for the tip in shortening the date calculation. It's so much tidier.
It also should evaluate a bit more quickly and this is nothing to sneeze at in FileMaker 12 solutions where screens tend to update more slowly than in version 11.