Is it possible to execute field actions for multi select?

When I click on a checkbox in my multi-select, I want to cause a field to show (un-hide) on the same form. I know this type of action can be done for many other field types. With multi select, putting in the usual "input.MultiSelectfield == "Selection"" in the "If" condition leads to a stringlist-string error.

Any way around this error?

Thanks