Trying to set up a new External Content Type that connects to a SQL database using a service account.
I have verified that the service account can actually connect to the DB because I used SQL Management Studio to log in to the external DB as the service account, and that worked.
Set up a secure store target application - the service account in question is in both the administrators group and the members group for the target application, and is the account used to "set credentials". (Went in and re-entered the credentials a second time to make sure I hadn't typo'd the password.)
When in Designer trying to create a new connection for the external CT, I get prompted once for username/password, I enter the service account and password, I then get prompted a second time, I enter the service account and password again, and then I get the error
Message from External System: 'Cannot logon with credentials obtained from Secure Store Provider.'.
What's going on? The service account has access to the external DB, proved by connecting using SQL Management Studio. The service account should have plenty of access to the secure store target application item because it is both a member and an admin for that item.
Any ideas why this isn't working, or where I could look next to try and troubleshoot this further?