SAP Message 63071 - Document & already cleared. Reversal not possible

Diagnosis
A clearing document already exists for the document with number &v1&(for example, an incoming payment has already been received). Thereforethis document can no longer be reversed.

System Response
The system cannot reverse this document. The reversal of the otherdocuments is not affected by this.

Procedure
Look at the document in financial accounting. If the posting wasincorrect, you might have to make a manual adjustment posting.