SLA Rule Not Working When Input Source Is Memo Line DFF

We have a requirement to assign different receivable accounts based on the memo line. In the Subledger Accounting (SLA) setup, we've specified the input source as the Memo Line DFF. For each memo line, we've selected the relevant DFF value as the natural account and want to use this value to derive the receivable account once the transaction is accounted. However, this approach isn’t working as expected.

Could anyone provide guidance on how to achieve this scenario?