How To Fix FMFG_BLEXT016 - Incorrect FM account assignment (&1) during service entry sheet posting

FMFG_BLEXT016 - Overview

• Message type: E = Error

• Message class: FMFG_BLEXT - Message class for BL extention for US Federal Government

• Message number: 016

• Message text: Incorrect FM account assignment (&1) during service entry sheet posting

What causes this issue?

When the US Federal extension of the Budgetary Leger (BL) is active, you
are not allowed to change the Funds Management (FM) account assignment
when posting a service entry sheet (SES).

System Response

For the US Federal Government solution, the budget statuses
"Undelivered/Paid" and "Delivered/Paid" have to be calculated. This
calculation is done using the BL payment creation, which has replaced
RFFMS200.
During an advance for a service purchase order line item, there is no
existing corresponding SES, so the down payment is posted to a specific
FM account assignment.
During the SES posting, the standard system allows the FM account
assignment to be changed; however, this is not a valid scenario in the
US Federal Government because the original service purchase order
account assignment is required for calculations.

How to fix this error?

You cannot change the original service purchase order account
assignment. Post the SES using the original purchase order FM account
assignment.
Having the same FM account assignment between a service purchase order,
the SES, and the invoice verification is a requirement even without
advances.

Procedure for System Administrators

The system issues an error message and will not allow you to continue with this transaction until the error is resolved.

Error message extract from SAP system. Copyright SAP SE.

FMFG_BLEXT016 - Details

• The SAP error message FMFG_BLEXT016, which indicates "Incorrect FM account assignment (&1)" during service entry sheet posting, typically arises in the context of Funds Management (FM) in SAP. This error occurs when there is an issue with the account assignment related to the Funds Management module, particularly when the system cannot validate the account assignment for the service entry sheet.
  Causes:
  
  Invalid Account Assignment: The account assignment specified in the service entry sheet does not exist or is not valid in the context of Funds Management.
  Incorrect Configuration: The configuration settings for Funds Management may not be set up correctly, leading to issues with account assignments.
  Missing Master Data: The master data related to the cost center, internal order, or other account assignment objects may be incomplete or missing.
  Budget Availability: There may be insufficient budget available for the specified account assignment, which can lead to validation errors.
  Document Type Restrictions: The document type used for