Math in display logic not working

I am trying to only show a question if a person's current age is equal to OR plus one their age during an event.

Without math, the equals part works fine. However, if I add the following math, it doesn't work:

If ${q://QID390/ChoiceGroup/SelectedChoices} Is Equal to $e{q://QID426/ChoiceGroup/SelectedChoices -1}

I've also tried making the second portion an embedded value, but that doesn't work either. If I pipe in the values into text, they look like what I"d expect.
Please help!