When I click the PDF Link form field in does nothing?

I want to add a PDF link to my email notification email but when I select the form field to add it to the form it does not do anything.  Why doesn't this work?

Hi,

I can see the PDF Link variable in your form notification. I can also add the form field variables.

Take note that when the Data Table is Lock, you have to click the Unlock Data Table button to add/edit the table. This feature becomes active when you enable the hide empty fields on email.

Hope this information helps. Thanks!