Can you confirm the volumes are correctly mapped to the iSCSI Target as well (iSCSI Targets --> Select the iSCSI Target --> LUN mapping -- and map the volume to the target). You may find detailed configuration steps for both Openfiler and VMware ESX hosts here: http://xtravirt.com/how-to-configure-openfiler-iscsi-storage-for-vmware-esx-4
<edited to add "LUN mapping">