>>Therefore, a rule of thumb: give your subclasses meaningful names, different from parent names.
>
>I made other research and i found the real problem:
>
>the real problem is the names of two subclassed class, the names are the same but the two classes are in different classlibrary.
>
>The scenario is the following :
>ClassLibrary CLASSES.VCX contain 'BASEFORM' Class based on VFP base Class FORM
>ClassLibrary BASE1.VCX contain 'BASE' Class based Class 'BASEFORM' of CLASSES.VCX
>ClassLibrary BASE2.VCX contain 'BASE' Class based Class 'BASEFORM' of CLASSES.VCX
>ClassLibrary B1.VCX contain 'SUBBASE1' Class based Class 'BASE' of BASE1.VCX
>ClassLibrary B2.VCX contain 'SUBBASE2' Class based Class 'BASE' of BASE2.VCX
>
>Issuing the following commands is possible to reproduce the behavior:
>
>MODI CLASS subbbase1 of b1 (close it) CLASSLIBRARY => base1.vcx
>MODI CLASS subbbase2 of b2 (close it) CLASSLIBRARY => base2.vcx
>MODI CLASS subbbase1 of b1 CLASSLIBRARY => base2.vcx <=== ERROR should be base1.vcx

So it seems to search the internal cache by classname only, not classname+classlib. Thing to watch out for.