@Charles-E if the FA is created based on Purchase Group during the PO Release, it is always created with valid from as the PO Release date. Maybe your supplier invoice has an invoice date that’s prior to the PO Release date.

Lets assume:

→ PO released → 6th of Dec → FA created with valid from 6th of Dec

→ Supplier Invoice has date 5th of Dec → when you will try to book this SI invoice with 5th of Dec, it will say it doesn’t find any FA valid on 5th of Dec.

To overcome this, you simply need to change the validity of your asset from Fixed Asset Object screen → this will automatically change the validity of the code part value.

Unfortunatly @Marcel.Ausan  the validity date of the FA starts on November 1st, and the date of the invoice and po is after this date.