When trying to create a SQL backup set, you click on the Discover button to populate a list of SQL servers present but none appear. Alternatively, a SQL server is populated but it is not the one you are trying to back up.
When setting up a SQL backup set, sometimes the Backup Agent fails to locate SQL instances on the server it is installed on. This may be due to permission issues or other factors, but it can usually be fixed by entering the SQL server address manually or running the Backup Agent service as a SQL administrator.
First, try running the Backup Agent service as a SQL administrator. If this does not fix the issue, you will need to enter the SQL server address manually. To do this, the address will need to take the form HOST\SQLSERVER. For instance, if the server where the SQL server is installed is called "Server01" and the SQL server is called "MSSQLSERVER" then the address will be Server01\MSSQLSERVER.