Thread:Extension talk:SkinPerNamespace/MediaWiki internal error

It doesn't work - what is the problem?

Original exception: exception 'MWException' with message 'Call to undefined method SkinCologneBlue::setTitle' in ../wiki/includes/Skin.php:1550 Stack trace:
 * 0 ../wiki/extensions/SkinPerNamespace/SkinPerNamespace.php(75): Skin->__call('setTitle', Array)
 * 1 ../wiki/extensions/SkinPerNamespace/SkinPerNamespace.php(75): SkinCologneBlue->setTitle(Object(Title))
 * 2 [internal function]: efSkinPerPageBeforePageDisplayHook(Object(OutputPage), Object(SkinCologneBlue))
 * 3 ../wiki/includes/Hooks.php(216): call_user_func_array('efSkinPerPageBe...', Array)
 * 4 ../wiki/includes/GlobalFunctions.php(3847): Hooks::run('BeforePageDispl...', Array)
 * 5 ../wiki/includes/OutputPage.php(1979): wfRunHooks('BeforePageDispl...', Array)
 * 6 ../wiki/includes/Wiki.php(406): OutputPage->output
 * 7 ../wiki/includes/Wiki.php(594): MediaWiki->finalCleanup
 * 8 ../wiki/includes/Wiki.php(503): MediaWiki->main
 * 9 ../wiki/index.php(58): MediaWiki->run
 * 10 {main}

Exception caught inside exception handler: exception 'MWException' with message 'Call to undefined method SkinCologneBlue::setTitle' in ../wiki/includes/Skin.php:1550 Stack trace:
 * 0 ../wiki/extensions/SkinPerNamespace/SkinPerNamespace.php(75): Skin->__call('setTitle', Array)
 * 1 ../wiki/extensions/SkinPerNamespace/SkinPerNamespace.php(75): SkinCologneBlue->setTitle(Object(Title))
 * 2 [internal function]: efSkinPerPageBeforePageDisplayHook(Object(OutputPage), Object(SkinCologneBlue))
 * 3 ../wiki/includes/Hooks.php(216): call_user_func_array('efSkinPerPageBe...', Array)
 * 4 ../wiki/includes/GlobalFunctions.php(3847): Hooks::run('BeforePageDispl...', Array)
 * 5 ../wiki/includes/OutputPage.php(1979): wfRunHooks('BeforePageDispl...', Array)
 * 6 ../wiki/includes/Exception.php(182): OutputPage->output
 * 7 ../wiki/includes/Exception.php(209): MWException->reportHTML
 * 8 ../wiki/includes/Exception.php(490): MWException->report
 * 9 ../wiki/includes/Exception.php(569): MWExceptionHandler::report(Object(MWException))
 * 10 ../wiki/includes/Wiki.php(506): MWExceptionHandler::handle(Object(MWException))
 * 11 ../wiki/index.php(58): MediaWiki->run
 * 12 {main}