I know you said you installed the kernel-source but the errors you reported are consistent with no kernel-source installed.
I don't remember if you have to have the correct .config as part of the kernel-source to get the module to build and install. The other thought is that if you do have the kernel-source installed that make dep may have to be done.
I switched to "stock" Linux kernels and I just don't remember what is needed to get the installed source and nvnet to compile cleanly with RH9 kernels.
Hope this helps ...