alternative hierarchy for cost centers

Hi all,

Due to reporting needs I have to work on two cost centers hierarchy at the same time. So I decide to use the alternative hierarchy which is a copy of the standard one. I've seen on help.sap.com that it was possible to copy the standard hierarchy, and to modify this new alternative hierarchy.

My problem is that the system doesn't let me modify the alternative hierarchy, I can't delete, replace or add any cost center.

Thanks in advance for your return.

Pascal