We have a Symantec Backup Exec SQL job that does nightly diffs and weekly full backups. Backup Exec was giving this warning after our jobs "Database is configured to maintain transaction logs. Transaction log backups are not being performed. This will result in the log growing to fill all available disk space. Regular log backups should be scheduled or the database should be changed to the simple recovery mode."
In order to resolve this, we created another job in Backup Exec using the "Log - Back up Transaction Log".
The strange thing now is that after these jobs run, both the Database and Logs grow after the backups run which has caused the disk to run out of space.