Mail.app no longer applies rules

[Eskadi]

Hi,

I am facing this apparently unexplainable problem: mail.app no longer applies the rules I defined sometime ago.

Mainly the rules are of the kind: if (any cond. are meet) (any recipient) contains {friend's name} then move the mail to {friend's name folder}.
This is to group every message from {friend} with any answer I wrote inside one dedicated folder.

Well, these rules do not seem to apply anymore. I don't know why. I have recreated them again (imagine the pain). Well, it did not work. And when I select a mailbox and choose to apply the rules again, after a moment, growl tells me xxx new messages. But sorting did not took place. Messages remains in their previous location.

Here is my setup:

1. One imap professional mailbox.
2. One pop3 yahoo personal mailbox
3. One imap gmail mailbox only used to host the directory tree of my message sorting system. (here are located the {friend's name folder})

Basically, message should go from mailbox 1 & 2 towards 3 when detected by the filter.

I also use Spamsieve 2.7.7 on the latest version of snow leopard and mail. app.
Brand new macbook pro 15", 2.8 GHz. (so I moved the mail.app data from a previous computer)

I hope somebody can help be.
Thx.