There are several factors that can make a payee unpayable (see Unpayable reasons). The payee's payable status displays beside the payee name on the payee record. Go to the "Payees" tab and search for the payee. Hover over the tooltip beside the payable status to see the reason why your payee is unpayable. Also check the account status of the payee. On the payee record, in the GENERAL row, look at the "Account Status" field, which indicates if the payee's account is currently active, blocked or suspended.