What Is The Prerequirements For Automatically GTIN Generate

Hello,

I want to use automatic gtin generate approach on the IFS V10.8.

• I created a record on gtin basic data like below.
• I created a record on company basic data gtin prefix like below.
• Then i checked a catalog part for generate gtin but the option is not active.

What should i do more, can somebody tell me prerequirements about automatically gtin generating.

Thanks.