It is possible for a tenant to have a zero balance yet be delinquent. This occurs when the tenant has a credit that is exactly the same amount as the amount they owe. In order to bring the account current you will need to make a payment to apply the credit.
To bring the tenants account current simply go to Make A Payment. Select Outstanding Balance and check the “Use Existing Credit” box. The total payment should be $0.00. Because no payment was received your bank deposit will not be affected.