SAP Message /SAPPCE/DPCM1221 - Posting not possible; chain & is blocked for postings

Diagnosis
Chain &v1& is blocked for postings. To post you must navigate to thecontract data and unblock the chain.

Procedure
Select Contract Data. The screen Display Contract appears.
To get to change mode, select Display -> Change
Select tab page Chain Status.
In the menu select Edit -> Unblock -> Posting.
Save your input.