How do you add an attachment to a Purchase Order?

One may attach any document to a PO manually without using the Document Management System in SAP, but no attachments can be added while you create a PO using ME21N. Save your PO and then open the PO using ME22N. There you can attach a document with the Service for Object button. Click the Service Object button –> Create –> Create Attachment then select your window directory, the file to be attached. This attachment is only for internal information. The system will not print this document automatically along with a PO printout.

Comments

I can't attach a document in a PO. I can see where the function is but it is blocked, I can't click on it cause its in gray caracters.
The consultants tell me that we have the standard version but I looked up in the internet and in the standard version, this option should be activated. Can anyone help me?
Greetings,

I recommend transaction ME23N (yes, Display) rather than ME22N. In Display mode, you can still add attachments. In Change mode, if you don’t actually make a change to the PO, the attachments can be lost.

I understand that this is NOT intuitive, but it IS SAP…