since I'm browsing I'll ask the std questions
did you install the kernel dev packages?
If you did, did you update the kernel dev packages via auto-update?
If you answered no to either of those questions, then that's probably the issue..
edit: from STEEL1.. instructions on installing the kernel dev packages
Step 2> Make sure you have the kernel headers installed along with all other dev tools - these are needed along with other dependencies. The best way to ensure that you have all dependencies is to just go start menu > system settings > packages > and in the development section choose the Kernel development packge and install the whole thing.