Billing is not created

Hi Friends,

Business scenarios:

I have created sales order 10 Tones, Delivery created 5 Tones, while doing Picking or PGI Truck capacity is only 3 Tones needs to be done PGI.

For that delivery I am trying to create billing it is not allowed.

Please provide the necessary setting.

Our side, We have activated split deliveries  and item category Billing relevance we have selected as K

Thanks

Vasu