Pier,

I worked on HP & AIX Oracle7.3.4 & Oracle8.0.4 but not SUN. Have seen
"BACKUP_DIR not set" before and that's usually due to Oracle not linked
properly. In my shop, relink is a DBA task and I have only performed it
once or twice so I don't have any more detail. But for those relink I've
done, there is no problem. Also, please check if connectagent is at the
latest fix level 2.1.7D.
Hope this will help. Thanks.

Regards,
Eric Tang