Diagnosis
You want to create a standard recipient list.
All the recipient lists in which documents in the standard recipient
list are used, are loched. This means that only one standrd recipient
list exists for a document.
A recipient list that is to be locked is currently being used byanother
user.

Procedure
You can delete the document from the standard recipient list.
Please make sure you delete the entries in the document number and
document type fields.