What ever you are compiling expects wxWidgets 2.6 you need to change it to use wxWidgets 2.8 or use wxWidgets 2.6 instead.
What version of Code::Blocks are you using? RC2 or SVN? If SVN, what number?
If SVN (also called nightly build), "Project" -> "Build Options" "Linker Settings" Under "Link Libraries" look for something like wxmsw26$(WX_SUFFIX) change the 26 to 28 so it becomes wxmsw28$(WX_SUFFIX).
Tim S