As last resort, I extracted my database in DDL and then reconstructed
it in a new file. Now by wonder i can create the unique key. Can
somebody explain me this?

Thanks, tom.

--- In ib-support@y..., "zifnabbe" <zifnabbe@u...> wrote:
> Hi,
>
> I get the following error when I try to create a unique constraint,
> what does it mean? :
>
> ISC ERROR Code 335544349
>
> attempt to store duplicate value (visible to active transactions)
in
> unique index "RDB$INDEX_16"
>
> I've emptied the table on which I want to put that constraint and
> I've nowhere set already such a unique constraint...
>
> Thanks, tom.