[Error] Kernel Module : No kernel module build environment

["Saman Ghannadzadeh" <saman@meninpc.co.uk>]

Hi,

I've been trying to install the official ATI driver for my graphics card,
but I get the following error:

[Error] Kernel Module : No kernel module build environment - please
consult rea$

The strange think is that the installation works fine in the 2.4.x kernel,
but in the 2.6.8-2-686 kernel it give the above error. I'm using Sarge and
i have the kernel sources and headers for 2.6.8-2-686 installed.

what oteh rpackage do I need to install? Where am I going wrong?