The DNS repoint of your .ie domain name failed because the nameservers are not authoritative for that domain. When updating the nameservers of a .ie domain name, a record needs to exist on the new nameservers before the change will be accepted. This is a requirement specific to .ie domains; the same does not apply to .com/net/org/info/etc domains.
To fix this and to be able to repoint your domain name, you will need to contact your hosting provider and ask them to ensure there is a DNS record set up specifically for this domain name on the nameservers. LetsHost cannot fix this for you, only the hosting provider responsible for the nameservers to which you are trying to repoint can ensure the record is in place. If you forward this email to your hosting provider, they will know what to do.
The check that is being carried out is not done by LetsHost, but rather by the IEDR. The same check is done on every .ie domain when being repointed, regardless of where they are registered.