Yes, that is probably a contributing factor.
You can find your version number in Help\About. It will be in the form of year.build (2007.000, 2003.16b3,...).
If you have 2007.000 or newer you can grab 2008.044 from http://www.matrixgames.com/products/325/do...r%27s%20Edition
Once you have installed that, grab 2009.042 from http://harpgamer.com/harpforum/index.php?showtopic=2049
In the off chance you are working with an earlier version than 2007.000 the newer battlesets won't work and you'll have to buy a newer copy of the game from MatrixGames.com if you want to use those battlesets.