Hello,

Been a few months since I've had to program a survey, and it's likely I'm just not remembering a step, but I'm having problems getting an exclusive option to work on a multiple choice question in Version 2.50+160823. Couldn't find my answer in the manual or expression manager so I'm asking here.

It's a simple enough question, labeled Q2, with 4 subquestions: Q2_1, Q2_2, Q2_3, and Q2_4.
Q2_4 is "None of the Above," so when it's checked, I want to disable the other three answers. I typed Q2_4 in the "Exclusive Option" in advanced settings, but it's not working. When I run a logic check I get the attached errors.

What other relevance am I missing?