SharePoint Online Secure Store

Hello - I’m trying to add an Azure SQL database through BDC to SharePoint. When I try to use the SharePoint Designer 2013 it is unable to connect to the external data page with an error about the connection being closed for BCS. When I try to add using the web interface (admin), I’m unable to add the password to the secure store and get a message saying that it is unable to add a key to the application server.

Can anyone help, all the articles I tried were aimed at SharePoint server rather than Online and didn’t work?