Chances are very likely the theme doesn't work with the current WPS syntax. You'll need to take a look at the
CustomWPS wiki page to check and see if there are any tags being used in the .wps for that theme that aren't listed, and if so, you'll need to remove them or replace them with the correct tag.
One that's almost a guarantee will be the %pb tag, it will need to be replaced with the correct syntax and the %P tag will need to be removed.
I believe you'll also have to at the very least declare one full-screen viewport since I believe text isn't allowed to be drawn on the default viewport anymore.
In short, the theme is very out-dated and will need a lot of tweaking and fixing to work with the current theme syntax.