Unable to find kernel sources

I'm trying to install the Parallels agent so I can use Transporter to make a VM from this Linux machine. Upon running sh Parallels-tsp-3.0.1456-lin.run, I get this error:

"Unable to find kernel '2.6.18-1.2798.fc6xen' sources" and it quits.

when I do a uname -a, this appears:

Linux nagios 2.6.18-1.2798.fc6xen #1 SMP Mon Oct 16 15:11:19 EDT 2006 i686 i686 i386 GNU/Linux

I've used yum to install kernel-devel, but this hasn't fixed the problem. It appears as though it installed different kernel source version inside /usr/src/kernels. It installed 2.6.22.14-72.fc6-i686. I'm lost at this point - where do I make my symlinks?

Any help would be appreciated.