[SLE] compiles for wrong kernel version

I've been running 2.4.0 for a few weeks. I recently pulled down 2.4.2, compiled it, and installed it. Things are working fine. However, I was playing around with a kernel module. After I compile the source with gcc, and try to load it up with insmod, I get the following error: kernel-module version mismatch test.o was compiled for kernel version 2.4.0-0.26 while this kernel is version 2.4.2. Any ideas on why I'm compiling for kernel version 2.4.0 when I'm running kernel 2.4.2? Thanks, Cory