[libvirt] Questions on "Xen XM error : internal error unable to store config file handle"

Dear all, I am trying to add defined domains to a hypervisor with virDomainDefineXML function. But I keep getting the following error. libvir: Xen XM error : internal error unable to store config file handle I tried using virsh, but it gave the same error. Does anybody know the cause of this error? Thank you in advance, /Taeho