Hmmm
append normally only applies to the first tape volume of a backup job. the second through xx tape volumes come from the scratch pool.
Did anything at all get backed up to the first tape?
If not, remember that in Veritas Speak, in order to be appendable, a tape volume must have an active backupset on it, be in the same media set as the job specifies, and be within the APP defined for the media set.
Also, remember that APP is calculated from the opening of the first backup set on the tape while OPP is calculated from the time the last backup set is closed.