IBM x3550 M3 with Debian Squeeze not detecting disks on installation

[Mauro Sánchez <mauroka@gmail.com>]

Hello.
I am trying to install Debian Squeeze on a IBM x3550 M3. The server
has this 3 disks:
IBM 600GB 10K 6Gbps SAS 2.5" SFF Slim-HS HDD

The RAID controller is a LSI 9240-4i

I have tried with a RAID 5 to install debian-amd64 but the
installation hangs up when it starts to format the disks.
After that, I tried with only one disk and non-raid configuration, and
the result is that the installation doesn't recognize the disk. It
gives me a list of the controllers that I have to choose, but the disk
is not recognized.

The server has all the firmwares updated, I know that because I have done it.

After all that, I have tried with Debian Testing and the installation
works just fine with no errors.
My question is, do I have to load some drivers for that kind of disks
during the installation?
What can I do? Should I try some other Debian installer like i386?

Thanks a lot for the help.
Cheers.
Mauro Sanchez.