Custom Area Page does not Exist

Hi guys,

Trying to create a custom area page but have hit page error:

Area Zxxxxx does not exist:

com.sap.pcuigp.xssfpm.java.FPMRuntimeException: Fatal error: Area Zxxxxx does not exist

at com.sap.pcuigp.xssfpm.java.MessageManager.raiseException(MessageManager.java:111)

Anyone has any idea why?