Help with Valid If required

[Chetty]

Hi folks,

I need a little help with a form I’ve created. One of the questions is of type enumlist however I don’t want respondents to be able to select all of the options.

The question I’m asking is ‘Have you made any of the following via the app:’

The options are;
Connections with a colleague
Buddy with a colleague
None

So basically if the respondent selects ‘None’ then they shouldn’t be able to select either of the other options and vice versa. I’ve read that this is achievable using the ‘Valid If’ field but I just can’t get it to work.

Any help with this would be much appreciated. Thanks!