But in some seconds my ISO domain is desconnected and it is impossible to Activate. I'm attaching my engine.log. The below error is showed each time I try to Activate the ISO domain. Before the upgrade it was working without problems:

2014-12-15 13:25:07,607 ERROR [org.ovirt.engine.core.dal.dbbroker.auditloghandling.AuditLogDirector] (org.ovirt.thread.pool-8-thread-5) [460733dd] Correlation ID: null, Call Stack: null, Custom Event ID: -1, Message: Failed to connect Host host1 to the Storage Domains ISO_DOMAIN.
2014-12-15 13:25:07,608 INFO  [org.ovirt.engine.core.vdsbroker.vdsbroker.ConnectStorageServerVDSCommand] (org.ovirt.thread.pool-8-thread-5) [460733dd] FINISH, ConnectStorageServerVDSCommand, return: {81c0a853-715c-4478-a812-6a74808fc482=477}, log id: 3590969e
2014-12-15 13:25:07,615 ERROR [org.ovirt.engine.core.dal.dbbroker.auditloghandling.AuditLogDirector] (org.ovirt.thread.pool-8-thread-5) [460733dd] Correlation ID: null, Call Stack: null, Custom Event ID: -1, Message: The error message for connection ovirt-engine.siee.local:/var/lib/exports/iso-20140303082312 returned by VDSM was: Problem while trying to mount target
2014-12-15 13:25:07,616 ERROR [org.ovirt.engine.core.bll.storage.NFSStorageHelper] (org.ovirt.thread.pool-8-thread-5) [460733dd] The connection with details ovirt-engine.siee.local:/var/lib/exports/iso-20140303082312 failed because of error code 477 and error message is: problem while trying to mount target

If any other information is required, please tell me.