HyphenSam If you don't want to upgrade your C2 version:
Just take his capx and extract it using something like winrar or 7-zip to a folder. Then in that folder open the caproj file with notepad/wordpad.
Then on the line
<saved-with-version>21000</saved-with-version>
Change that number to your version. If your version is 206 then the number should be 20600, if your version is 200 then change it to 20000, if 207 change to 20700, etc...