Linux backup command for Full and Differential

Hi,

Platform: NW Server WIN2K3R2. NW 7.3.3 (Build 510). Client SUSE 10.x

I have tree clients (1xWindows and 2x Linux ) in a group. I ran a full backup on Friday and trying to run Diff backup (Level 1) on Tue/Wed/Thu ( No Week End). My Window backup appear to be running according to my schedule. My linux client is doing a FULL backup everyday- totally ignoring my schedule. I am doing all my configuration via the Mgmt Console.

How can I get my Linux to do a full backup on Fri and Diff the rest of the days?

BTW: I have tried the admin guide!! and Google.

Thanks
Habib