Invoices are designed as one-off wage payments that international and domestic contractors send to their clients.
Direct Deposits are designed as an employment contract, with the same wage payment amount sent each pay period, that domestic employees specify with their employer.
If you are only able to create a Direct Deposit but want to create an Invoice (or vice-versa) follow these instructions:
First go to Contracts under External Invoicing
Click on the relevant Contract, but click on the grey area to edit the Contract
Change the Job Role to Domestic or International Contractor for Invoices, and Domestic Employee for Direct Deposit
Now you can create Invoices and Direct Deposits, depending on your job role.