incremental backup grows larger and larger

[Nina Pham]

Our amanda server backups itself and backup another host machine which 
runs amanda client.  We run incremental backup 6 days a week and full 
backup 1 day a week (incremental backup is not ran on that day). Reading 
the logs, size of files backed up from amanda server is growing till the 
full backup day, and going back to small on the incremental backup day 
after full backup day. However, the totol size of files backed up from 
the amanda client host machine keeps growing. It doesn't seem to care 
about the full backup I think, but I don't know what mistake that I made 
in configuration. Any body has any idea? Thanks.