>QueryUnload fires only under the following circumstances: CLEAR WINDOWS, RELEASE WINDOWS, or QUIT commands are encounter or the user selects the close option from the control menu or the use clicks the close (X) box. It doesn't fire when ThisForm.Release is issued. That's why any issuing of ThisForm.Release often is done in this fashion:

IF ThisForm.QueryUnload()
>  ThisForm.Release
>ENDIF

There are quite a few ways of handling form closure, it seems. I usually just avoid code in the Release() method, personally, that's one way. Also, if you do want code in the Release, you can have a "redundant" Release call in the Queryunload:

IF some_condition
  NODEFAULT
   ...
ELSE  
  ThisForm.Release  && causes no trouble, but fires Release
ENDIF