[Users] CLI: can't attach storagedomain

Hi, I have an iso domain created during engine setup. But I can't attach it to the datacenter in cli. oVirt shell (connected)]# create storagedomain --name "fc16-lid-engine_iso-domain" --datacenter-identifier "ac2690e4-72b2-11e1-882d-000c29bf47ca" unknown error: status: 400 reason: Bad Request detail: [Cannot attach Storage Domain.] Any ideas?