Hi Fabio,
I didn't get your issue.
But in general you first need a BADI Definition, from which the BADI Interface will be generated. There are some options in the BADI Definition, for example, if you can have only one or several active Implementations.
You can only create a new implementation and activate it, too, if the multiple active implementations setting is set in the definition.
If this setting is active, after creating the new implementation don't forget to activate it.
Regards,
Klaus