Answer:
Is the button enabled or disabled (greyed)?
If the button is disabled:
The sub-document doesn’t exist (check the folder: …\puser1\Design)
If the button is enabled but when it click it does nothing:
Check the Preference (“Word Processing Software Executable”)
Check that there is no instances of Word in use (start Task Manager)
In both cases:
Exit from APV
removed Design.rtf file under puser1
removed …\puser1\Design folder
rerun APV
rerun calculation.