this button is created on which table and what condition you wish to add? based on which field of that table?
Refer this OOB "Resolve" form button on incident table and the condition is applied in Script condition field
You also try adding it in script condition field, although it should work fine in record condition
something like this in script condition
current.stage == 'Your Stage Value'
If my response helped please mark it correct and close the thread so that it benefits future readers.
