I encountered this problem :

In the method init of a form I put the instruction "On error do loc_err with(error())"
this routine would prevent the system by giving me the error 1884 ( "Uniqness of index violated")
But if I generate a record with a duplicate key the error routine is not processed.

Here is the error procedure :

******************
Procedure loc_err
parameters errno
if errno = 1884
=tablerevert(.f.)
else
.........
endif
******************

But it is not processed

Thanks
Alessio