SET SBTDUTIL=ON

Upper case, no spaces. Even then it will only debug whern running fill VFP and you have to have source. If you really want to make sure the debug environment is correct, re-compile all the files -- but make sure to do so from the SBT root (i.e. 'compile so\*.prg', not 'compile *.prg' from SO directory), because there are some #INCLUDE files in the root.

- John Kiernan