Are you sure you installed the correct wx version? that is, 2.4.2 or 2.5.1? Are you sure you uninstalled any previously installed or compiled/installed wx version?
This howto has been tested on about twenty different debian systems, and works fine. What's more, I use Debian/Testing too. So I guess there's some step wrong when you're following the howto or some weird config in your system.
Greetings!