[Dovecot] Sieve problem with managesieve

[Simone Caruso]

I have a problem with a sieve script..
my config is dovecot 1.2.15 with managesieve, and roundcube.

Now i have this script WORKING:
--
require ["fileinto"];
# rule:[TracSvil]
if anyof (header :contains "From" "x...@example.com")
{
        fileinto "INBOX.Trac Svil";
        stop;
}
--

And this script NOT working:
require ["fileinto"];
# rule:[TracSvil]
if anyof (header :is "From" "t...@ardeek.com")
{
        fileinto "INBOX.Trac Svil";
        stop;
}


Can someone explain me the difference between these script? there is any error 
in the second script?

Greetings!

--
Simone Caruso
IT Consultant
p.iva: 03045250838