I have ubuntu 12.04
$ lsb_release -rc
Release: 12.04
Codename: precise
$ uname -a
Linux pablo-desktop 3.2.0-20-generic #33-Ubuntu SMP Tue Mar 27 16:42:26 UTC 2012 x86_64 x86_64 x86_64 GNU/Linux
I have installed virtualbox 4.2, I try make a virtual machine with debian amd64
http://cdimage.debian.org/debian-cd/6.0.4/amd64/iso-cd/debian-6.0.4-amd64-netinst.iso
but only work with a debian i386
http://cdimage.debian.org/debian-cd/6.0.4/i386/iso-cd/debian-6.0.4-i386-netinst.iso
why?