What's wrong with my SQL code?

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select invoice_number, invoice_total, (payment_total + credit_total) as 'payment_credit_total', (invoice_total - payment_total - credit_total) as 'balance_due'

having (balance_due > 50) order by balance_due desc limit 5;

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I'm getting a syntax error and I'm not sure what I'm doing wrong.

Thanks.