SAP Message /SAPPCE/DPCM1222 - Posting not possible; missing account assignment data in contract data

Diagnosis
No account assignment data is specified in the contract data.
To post, navigate to the contract data and define the G/L accounts youwant to post to for this down payment chain.

Procedure
Select Contract Data. The screen Display Contract appears.
To get to change mode, select Display -> Change.
Select tab page Account Assignment.
Specify at least one G/L account in conjunction with a WBS element
Save your input.