SAR CRM CASE MANAGEMENT Transfer Docs Button

I have a requirement where the user would like to see all the documents attached to all the Tasks created as follow-up documents of the Case in the Attachments AB in the parent Case itself. So, If the Case has 3 Tasks with 2 attachments each, then I should see the 6 attachments in the parent Case.

I saw that in the Attachments AB of the Case, on each line, there is a button called "Transfer", where you can transfer the documents attached to the Task as a link or as a copy, to the Case.

The problem is that when I try that option, I am getting the message "No reference data available for fund usage CRM_FM_ACL095".

Any idea on what is missing in order to make it work?

Thanks in advance.

Regards,

Anant