How to restrict workflow transition screen based on custom field value

[U]

New transition screen that has been configured should be popped up based on the custom field check box named as “Exists in Production”

• If “Exists in Production” is selected then this transition screen should appear upon clicking on the workflow transition “Start Fixing”.
• If “Exists in Production” is not selected then workflow transition should be processed upon clicking on “Start Fixing” without this screen pop-up. 

Can you suggest implementation methods for this.

[Nic Brough -Adaptavist-]

Create two transitions

• one with a condition of " 'exists in production' is empty" and with no transition screen
• one with a condition of " 'exists in production' is  not empty" and with the transition  screen