lvm volume group problem

I have a stanza in my autoinstall.xml file that looks like this, and the partition is getting created and flagged as an LVM partition, but the volume group is not being created. Additionally, I still have to run pvcreate on the partition before I can do a vgcreate with it. Am I missing something? <partition> <lvm_group>vg0</lvm_group> <partition_type>primary</partition_type> <size>max</size> </partition>