When synchronizing with QuickBooks you may receive the following error - Invalid reference to KlassList in ClassRef. The error also includes the name of the class that Projector is expecting to find in QuickBooks.
or 
You should make sure that the class exists in QuickBooks and matches the cost center in Projector.
Solution
Find the cost center for this transaction and edit it. Then verify that the Cost Center column matches the class name in QuickBooks.
