[ovirt-users] Unable to attach ISO domain to Datacenter

I'm having trouble to create a storage ISO Domain and attach it to a Datacenter. It just give me this error message: Error while executing action Attach Storage Domain: Could not obtain lock Also the oVirt's Engine log files show this error message: "setsid: failed to execute /usr/bin/ionice: Permission denied", but I was unable to identify what exactly it's trying to do to get this permission denied. 2019-11-14 16:46:07,779-03 ERROR [org.ovirt.engine.core.dal.dbbroker.auditloghandling.AuditLogDirector] (EE-ManagedThreadFactory-engine-Thread-7388) [86161370-2aaa-4eff-9aab-c184bdf5bb98] EVENT_ID: IRS_BROKER_COMMAND_FAILURE(10,803), VDSM command AttachStorageDomainVDS failed: Cannot obtain lock: u"id=e6b34c42-0ca6-41f4-be3e-3c9b2af1747b, rc=1, out=[], err=['setsid: failed to execute /usr/bin/ionice: Permission denied']" This behavior just happens on ISO Domains, while Data Domains works fine. I have read oVirt documentation and searched everywhere but I was unable to find the solution for this issue. I'm using CentOS 7 with last update of all packages (oVirt version 4.3.6.7). Please help! Thanks, Ivan de Gusmão Apolonio