AP open interface invocie_type_lookup_code empty

Hi.

I'm traying to import a invoice trough open interface.

In field invoice_type_lookup_code have uploaded the value 'STANDARD' the import proccess end up ok, but when I see the invoice the field invoice_type is empty and field is protected for update.

How I can to make so that the field invoice_type_lookup_code is completed with open interface.

I already tried with the field empty, but in the invoice is empty too.

Thanks