Adding Edit List command to list of Sales Credit Memos

In the RTC I am trying to add the ribbon Command, “Edit List” to the list of Sales Credit Memos. The procedure I’m doing: click Customize Ribbon. In Show actions in this order, expand and then click Manage. In Available actions, expand Manage, click Edit List. Select Add. The Edit List command shows up under Manage. Move it to the top of the list. Click OK.

The command Edit List does not show up on the Ribbon in the Manage section. WHY?

If I do these same steps for Sales Invoices the Edit List command displays on the ribbon.

Thanks for the help

A customer’s license does not allow modification of that table (114). And several other tables as well.
The license states (RimD) meaning Direct Read and Delete, but indirect Insert and Modify.
You cannot change this.

With indirect permission a (proper) developer (you?) with a developer’s license may create e.g. an object (page, report or whatever) with property Permission sat for that table-id.
Doing this is extending an indirect permission.