we have a problem about MS SQL 7.0 backup

Our system is as follows;
we have master server on NT and Netbackup' version is 3.2, patch J0820363.
client's machine is on NT 4.0 and Netbackup 3.2 & Netbackup client for MS
SQL Server 3.2, patch J0820363.

DB is about 1G.
In batch file database backup and trasanction log backup.
we had schedule backup about batch file

first day, Backup was successfully completed. but Database backup's elapsed
time was about 9 hours.

next day, Database backup was failed with error 0 and then Transacton log
backup was successfully completed.

we must resolve this problem until Thesday servcie start day before.
please, I wish your answer