[exim] Problem with DomainKey

Hi, list!

I tried to implement the DomainKey on a test-domain...
Then I configured Exim with a transport that sign the E-Mail.

And then, I sent a test E-Mail to an account by yahoo.de.
I think, Yahoo must know how to treat an E-Mail with domainkey...

So, I received my test E-Mail, but in the Headers I see:

X-Apparently-To: test.lucabert@??? via 217.146.182.102; Sat, 09 Jun 2007 06:27:27 -0700
X-Originating-IP: [62.75.208.62]
Authentication-Results: mta126.mail.re3.yahoo.com from=lucabert.com; domainkeys=temperror (cant get key)
Received: from 62.75.208.62 (EHLO mail.lucabert.de) (62.75.208.62) by mta126.mail.re3.yahoo.com with SMTP; Sat, 09 Jun 2007 06:27:26 -0700
DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=2007; d=lucabert.com; h=Received:Date:From:To:Subject:Message-ID:In-Reply-To:References:X-Mailer:X-Face:Mime-Version:Content-Type:Content-Transfer-Encoding; b=JeO2mnmLidtCykVELEXetKspsNKiLAHIpFIkquAKX2BF6NOkOFM0jUyruKOJ7WGqNb4Iv+EkhIs+KTiRjH1f8qzTKpEHiJnSTpOpaolzu+b8I8w4eMFQfI/1BMalN+c/;

Now: why says yahoo "temperror (cant get key)"?

In my domain lucabert.com I configured an entry _domainkey.lucabert.com and a
selector 2007._domainkey.lucabert.com.
If I query the DNS I get:

[lucabert@ns lucabert]$ host -t txt _domainkey.lucabert.com
_domainkey.lucabert.com text "t=y\; o=-\; r=postmaster@???"
[lucabert@ns lucabert]$ host -t txt 2007._domainkey.lucabert.com
2007._domainkey.lucabert.com text "k=rsa\; t=y\;
p=MHwwDQYJKoZIhvcNAQEBBQADawAwaAJhAKrIfWelo+CMd3wwmkR7M33nkW6IKX2xT4mWJNZ/9YkD9YTUiFF3UCQKWf0tgQJnT/jqyNUcDQVDgX0fmLhv4PaBgJEMj6b/MjdEoMXWYG+S7iGp8yOg+CheRhOWtYx7GQIDAQAB"

Can someone help me?

Thanks a lot
Luca Bertoncello
(lucabert@???)