Error Message Posting a Non-PO Vendor Invoice

The instance is ECC 6.0.

While trying to post a non-PO vendor invoice, I am getting the below error message:

"RKEAK-FIELD(12) is not an input field

Parked document could not be posted 00 S 347 RKEAK-FIELD"

Does anyone ever bumped into the same error message or have an idea what is generating the error?

The issue started happening after one of the accounts in posting (Vendor Discounts) which is a CE was changed to post to Profitability Segment in OKB9. This error was not faced earlier when the account was posting to Cost Centers.

We are using new GL and Doc Splitting functionality.