Did You Switch from 2.0 to 3.0
The 3.0 financial module is a full accounting module. Take a look at this article to get you set up for full accounting.
To Adjust a Few Transactions
Be sure that the activity, facility, addon's and discounts all have revenue codes set.
To manually update a specific transaction, view further instructions.
To Check Items
Items may be missing codes go to Configuration / Financial Settings / GL Configuration / Transactions Needing Attention and Items with Missing GL Codes
Make sure you are set up correctly - view the financial section!