To successfully back up a database, its mode in SQL needs to be set to "Normal".
To add to or remove databases from the Intronis Backup Set, the databases need to be set to "Normal" mode. You can make the change to the database mode within SQL Management Studio.
In addition to having the database set to Normal mode, ensure that the AutoClose option is disabled for each database you want to back up.
AutoClose shuts down a database when the last user logs out, which prevents Intronis Backup from accessing the data to back up.
SQL cannot backup databases that are in "Shutdown" mode.