Unable to login into UCES with FI User Management configured in XCM

Hi Everyone,

I've been going through a lot of UCES documentations and found the below Help Link:

User Management in Contract Accounts Receivable and Payable - Configuration of SAP Biller Direct for FI-CA - SAP Library

In the above SAP help link, it is recommended to configure the User Management Engine (UME) in such a way that the authentication is made against an SAP system, if using FI UserManagement.

But in our scenario, we have UCES installed on Portal server and Portal's UME is configured to use Web AS Java database instead of ABAP Data source as suggested above.

Could it be the reason that even after configuring FI UserManagement in XCM for UCES, the user authentication is not successful through SAP system (Authentication Failed appearing) and on the contrary they are authenticated through Portal UME (Web AS Java database) without an issue.

Is it mandatory to configure the UME of Java server (In our case Portal server where UCES is installed) with ABAP data source (SAP System where FI-CA is installed) so that users can be authenticated against SAP system instead of Portal UME.

Please provide your valuable inputs so that we can arrive at a conclusion and take a decision accordingly.

BR,

Anurag