>At home on a machine with VFP 5.0a ,local data, I build an '.app' file. When I issue a 'SET STEP ON' I get a "FEATURE NOT AVAILABLE" error.
>
>However, at work with VFP5.0a installed , local data and using an '.app' file I issue 'SET STEP ON' and it activates the debugger with no problems.
>
>Why no errors at work? but errors on home machine?
>is it some kind of environment setting i am missing?
>Any Ideas?

Are you running the Developers version of VFP at home? If you're only running the Runtime, you don't have access to the debugger.