Hi,
when I whois my domain name the lookup tell me that
my DNS are not authoritative...

It seems that there is no error on my linode dns manager.
Why I got this error?

Thanks!

The DNS servers that linodes use for lookups are not the same DNS servers that are used to host your domain's DNS. Since they are not the same server, they are not authoritative and are just giving you back their cached information. Unless there is some other problem that you are not mentioning, then this is normal behavior.

If you want authoritative information, you need perform your query against the authoritative server, such as:

nslookup domain.com ns1.linode.com

or

dig +trace domain.com