Post Goods issue mandatory for Service items prior to billing

Hi All,

Kindly need help for the below.

When We create delivery for service items ( material is Dien without quantity and value update ) ,and do PGI for the same , Confirmation of service documents is created after which Invoice/billing will be created.

Here the requirement is , User should not be able to do Invoice without doing PGI , which is allowing to do so as of now.

Regards,

Shashi