Unable to create cost center heirarchy

I am trying to create a new cost center hierarchy but i keep getting the following issues:

When I try to create the first node by copying an existing node in tcode OKEON I get the error below:

Overlapping intervals or identical values have occurred

then when i try to save it I get

Cost Center Group ATOT_1097 does not exist

Not sure what I can do here:

If I try and create the hierarchy from Tcode KSH1 then I am unable to view the structure in OKEON.

I am also unable to assign a new cost center to that heirarchy...............

Where am i going wrong...........