1. Log into database with a user with Sage 300 ERP admin rights.
2. Double-click on Common Services.
3. Double-click Fiscal Calendar.
4. Select the appropriate year.
5. Double-click on the field Unlock Column for the period to be unlocked.
6. Repeat step 5 for each period to be unlocked.
7. Click on Save.

Try posting the sub-ledger batch again.