wbadmin keep only 3 versions of systemstate backup

Hello,

I have backup established via wbadmin. I start backup with command "wbadmin start systemstatebackup -backuptarget:D:", by this command I will create maximum 3 versions. When 3 versions exist and I run the command, the oldest version is deleted.

What I'm missing here? Why the oldest version is deleted? I want to keep more versions.

The OS type is: Windows Server 2008 R2 Enterprise.

Thanks in advance,