mimetypes in fedora rpm version

[marswaco]

I'm newbie in this kind of issues; also my english is a little rusty, but i'll try to make understand.
I was using the Fedora 8 rpm version 0.2-5 beta ( obviously installed in fedora 8 ) , and I encountered the problems of the mime misdetection of some file format/extensions; so i try to move to another version of roundcubemail of fedora, in these new versions i still have the exact same problem like the originally 0.2-5 (the files attached are in the mails are misdetected and treated like plain/text).  
Looking a little the rcube_shared.inc i started to think that the problem is generate by the location of the file mimetypes.php, changing the owner or the permission of the file makes no difference. Also i've tried with rpm 0.2.2 but nothing changed.
Changing to tar.gz version solves the problem; but I'd like to stay in rpm version as long as posible.
Any help will be well apreciated.