AMD Catalyst installation woes on Slackware

I'm trying to get my ATI graphics driver installed on my fresh Slackware OS (Zenwalk). I'm coming from Ubuntu 14.04-14.10, so I know there's a whole lot I don't understand just yet.

I download the .zip archive from here, then unzip it to extract the .run file.

sh amd-driver-installer-catalyst-13.1-legacy-linux-x86.x86_64.run --buildpkg

generates the following output:

Created directory fglrx-install.hu4jBU
Verifying archive integrity... All good.
Uncompressing AMD Catalyst(TM) Proprietary Driver-8.97.100.7.........
=====================================================================
 AMD Catalyst(TM) Proprietary Driver Installer/Packager 
=====================================================================
Generating package: Slackware/Slackware

ATI SlackBuild 
-------------------------------------------- 
by: Emanuele Tomasi <tomasi@cli.di.unipi.it> 

AMD kernel module generator version 2.1
kernel includes at /usr/src/linux/include not found or incomplete
file: /usr/src/linux/include/linux/version.h
ERROR: I didn't make module
Removing temporary directory: fglrx-install.hu4jBU

Using the command ./amd-driver-installer-catalyst-13.1-legacy-linux-x86.x86_64.run runs the GUI setup, but results in the same error. I'm not sure what to make of this error, or what steps I should be taking. Any assistance is appreciated.

If it matters, uname -r = 3.14.5