G2N - Item Category - Not relevant for Billing

errore-message.pngHi SAP gurus

I have an issue in SAP S/4HANA. I have associated to my credit memo sales order type the standard item category G2N, for order related billing. have set billing document, copy control and all the settings, but when i try invoicing the item the message "the item is not relevant for billing" pops-up, compiled as per attachment.

Does anyone have any suggestions on how to fix this?
Thank you