Specify a date within the permissible range
From the SAP Business One Main Menu, you have chosen
and have entered the relevant customer and item information.You specified a posting date and a due date in the same posting period, for example 2009.
You have specified a document date in a different period, for example, 2010.
To add the document, you have chosen OK.
Specify a due date and document date that fall into the same posting period as the posting date.