Hide/show select form field using depends_on

I have a custom select field “issue_type” that I’ve added to the issues form.
I am trying to show/hide another select field (names) based on issue_type having a particular item selected in it.

In the second field “names” I have added this to the depends_on field:

issue.issue_type==“An issue type”;

But selecting “An issue type” from the issue type select does not then show the names select field. Can anyone assist?

I have tried adding eval/doc. as per this:

Try:

eval:doc.issue_type=='An Issue Type'

I have a checkbox located in a different section break and a dependent field in a different section break . how to put the Mandatory Depends on code in customize form ?