Data element: change documentation not allowed

Hi,

I'm installing SAP note 1738700 regarding SEPA mandate, and one of the manual steps requires the modification of a data element (SEPA_MNDID) documentation.

In SE11, when I click on the documentation button (Ctrl+F7), a new window pops up, to type in the name as general text. There are two radio buttons (Original text and Template with headers).

If I type in any name, let say DOC_SEPA_MNDID, I receive an error message: "Enhacement name DOC_SEPA_MNDID violates the namespace convention (989653)". It happens choosing any of the mentioned radio buttons.

I referred to that note, and then I used the name ZDOC_SEPA_MNDID, and I can access the general text screen to write in the text proposed in my note. But when I try to save using the package BF_SEPA, I receive an error message stating that "it's not possible to assign client object DOCT ZDOC_SEPA_MNDID to package BF_SEPA", and therefore I cannot create the required documentation to fully install SAP note.

I also tried through SE61, but there it says data element SEPA_MNDID does not exist, and cannot make changes there neither.

Do you have any idea of what should I do to successfully change the documentation of this data element?

Does it have anything to do with the language I'm logged in and in which I'm making the changes (ES)?

Thank you