[Exim] (no subject)

I run exim 3.35 on a debian-woody server.
I have more than one domain.
I use aliases files for each virtual domain.

I post a message to toto@???.
When the alias exist only in one alias file, the mail go to the good user.
When the alias exist in the main domain file and in another alias file
(for exemple for the main-domain.com and for domain1.com), the mail go to
toto@??? even if it is send to toto@???...

What's the problem?...

Thank's for your answer.

E.Bullier