Incremental backup still doing full

[Hermes101]

Hello,
made several simple tasks, like:
From one folder to another
Backup type: Incremental
Schedule type: Daily at 22:00
Dynamics:
full copies to keep:2
Make one full every: 10
but Cobian doing full backup every day! What am I doing wrong?

Thanks in advance

[cobian]

Is the Clear archive attribute on the Advanced tab set?