Hiii Srini K
Create a new asset in As01 and don't save it and . Check the depreaciation areas in the last tab.If they are visible, then only reason is it was deactivated manually as per my knowledge
If not visible, then check OAYZ and also check if dep area is deactivated/ Activated or not and for dep key config.. check AFAMA and AFAMS
Regards,
Abhay