SQL 2005 Tran Logs not truncating

Here is the sql script for the db backup

BACKUP DATABASE [FCE] TO DISK = N’\\JUM1\GPBackups\FCE nightly backup’ WITH INIT , NOUNLOAD , NAME = N’FCE nightly backup’, NOSKIP , STATS = 10, DESCRIPTION = N’FCE nightly backup’, NOFORMAT

The back up runs but the tran log backup just keeps getting bigger. The actual tran log file is not large.

If I do a manual backup in the database itself separate from the maintenance plan it truncates normally. What is wrong with the attached script?

Help! Why?

Joanne Mahoney