Wix Forms conditional rules

Hello,

I am trying to set up the following Wix Form conditional rule, without success:

By selecting a specific option of a dropdown field, it should automatically show a previously (by default) hidden text field.

In other words, I would like to know whether it is possible to have a field hidden by default, but show up under a certain conditional rule.

Any help would be really appreciated!

Thank you,

Manos