[GL] Balance Sheet Not Balancing?

First check: Go to General Ledger>Programs>GL Account Parts

Go to the Instances Tab and make sure all GL accounts have a major and minor category assigned

***If cost is put to a GL account that is not assigned categories, it will not show up on financial reports

View GL Account Parts Article for more detail: [GL] GL Account Parts and [GL] GL Report Categories

Second Check: Verify that there was not an unbalanced journal entry posted 

Go to General Ledger>Programs>GL Company Parameters

Check that the 'Allow Unbalanced Entries' is not checked

To view all journal entries, go to General Ledger>Reports>GL Journal Transactions - Landscape

Review that all journal entries are balanced

Third Check: If it is the beginning of a new year, you may have to run GL Beginning Balance Update

Go to General Ledger>Programs>GL Beginning Balance Update

View the beginning balance update article for more details: [GL] GL Beginning Balance Update