[Users] Could not login into the iscsi domain

Hi guyz, I have setup my ovirt engine with NFS as datacenter storage, so the default datacenter has nfs storage. Now have created a test datacenter inside ovirt with Type = iscsi. When I try to add new storage domain to this datacenter, I am able to discover the Lun but could not log in. Any help will be much appreciated. Thanks Saurabh