Error "Failed to Detect Operating System"

Hi,

When I want to install Virtualmin, on a Debian 4.0r2, my mistake
INFO - Download of http://software.virtualmin.com/lib/oschooser.pl Succeeded.
INFO - Loading OS list ...
22:38:15 URL: http://software.virtualmin.com/lib/os_list.txt [3492/3492] -> "os_list.txt" [1]
INFO - Download of http://software.virtualmin.com/lib/os_list.txt Succeeded.
Failed to Detect Operating System

Have you any idea?

Thank you