Squirrelmail and postfix

Hello out there, with this question I'm not realy sure where can be the
mistake. I've postfix running with no problems, but when the users (in
this case, just me) use the web interface to check the email, the
messages doesn't show the sender, date or subject.
Only a line like this is shown:

From sort Date sort Subject sort
Unknown Unknown date (no subject)

That's very weird, because inside the email I can see the sender, date,
subject and message body without any problem.

Maybe squirrelmail is getting problems, because if I send an email from
my own server to gmail por example, I can see the sender name, date and
the subject. And, if I reply the mail from gmail to my server, can't
see the sender, data and subject.

Does anybody know anything about this?
Any help will be well recived.