This usually means that the journal lines themselves do not balance back to the same value for debit and credit. Please check this using the following:
Select the journal you are trying to post in the batch screen
Select the Edit button
Inspect the journal lines carefully and ensure that the total of debit values match the total of credit values.
If you have checked the journal and confirmed that both columns balance to the same value in Dimensions, our support team will need to investigate, run scripts or liaise with the hosting or development teams. Any Issues with contacting us, please see the following Get support in Dimensions.