DFF freetext default value

Summary:

how to achieve this requirement for DFF2?

DFF1, ATTRIBUTE1: value set containing 'Yes' and 'No'
DFF2, ATTRIBUTE2: freetext

DFF2 default value:
when DFF1 = Yes, then empty
when DFF1 = No, then 'X'

tried using this SQL default value, did not work

select
case
when :{SEGMENT.ATTRIBUTE1} = 'No' then 'X'
end
from
dual

Content (please ensure you mask any confidential information):

Version (include the version you are using, if applicable):

24B (11.13.24.04.0)

Code Snippet (add any code snippets that support your topic, if applicable):