EAI Insert Error Siebel 19

Hi experts,

I'm having the following issue:

I've built a WF that has 2 steps: Datamap, and Insert.

The objective of this wf is to create in Siebel an Order with data received from an external system.

The Datamap executes fine. I'm using as Destination IO: PDS Order.

The issue is whit the Insert step. I get the following error:

ORA-01400: cannot insert NULL into ("SIEBEL"."S_ORDER_BU"."BU_ID")

SBL-DBC-00111: An error has occurred writing to a record. Please continue or ask your systems administrator to check your application configuration if the problem persists.

I've tried changing in the Datamp the destination IO to SIS OM Order, but I get the same error.